Researchers Database

SATO, Hisako

    Graduate School of Science and Engineering Engineering for Production and Environment Professor
Last Updated :2020/10/21

Researcher Information

Research funding number

  • 20500359

J-Global ID

Research Interests

  • キラリティ   D-アミノ酸   Clay Langmuir-Blodgett Method   Vibrational circular dichroism   Supramolecular chirality   Chiral tectonics   Inorganic-organic hybrids   Clay minerals   センサー   トランジスタ   イリジウム錯体   伝導性   ニオブ酸ナノシート   無機材料   ナノシート   電子デバイス   ダイオード   合成サポナイト   層状化合物ナノシート   層間・層状化合物   光伝導性   層状・層間化合物   光電流   光学分割   粘土鉱物ナノシート   酸素センシング   発光   

Research Areas

  • Nanotechnology/Materials / Nanomaterials
  • Nanotechnology/Materials / Analytical chemistry
  • Nanotechnology/Materials / Inorganic and coordination chemistry
  • Nanotechnology/Materials / Basic physical chemistry
  • Nanotechnology/Materials / Functional solid-state chemistry
  • Nanotechnology/Materials / Inorganic compounds/materials chemistry

Academic & Professional Experience

  • 2010 - Today  Ehime University大学院・理工学研究科教授
  • 2014 - 2016  東邦大学理学部客員教授
  • 2009/04 - 2010/03  Ehime UniversityGraduate School of Science and Engineering准教授
  • 2006/10 - 2009/03  Japan Science and Technology Agencyさきがけ研究者(東京大学大学院理学系研究科)
  • 2003/03 - 2006/09  Japan Science and Technology AgencyCREST研究員(東京大学大学院理学系研究科)
  • 2002/07 - 2003/02  The University of TokyoGraduate School of Science研究員
  • 1983/04 - 2002/06  日立製作所勤務
  • National Institute for Materials Science

Education

  • 1981/04 - 1983/03  The University of Tokyo  Graduate School of Science  Department of Chemistry
  • 1977/04 - 1981/03  Waseda University  School of Science and Engineering  応用化学科

Association Memberships

  • モレキュラーキラリティ   低次元光機能材料研究会   THE SOCIETY FOR REMEDIATION OF RADIOACTIVE CONTAMINATION IN ENVIRONMENT   JAPAN SOCIETY OF COORDINATION CHEMISTRY   THE CLAY SCIENCE SOCIETY OF JAPAN   THE JAPAN SOCIETY OF APPLIED PHYSICS   THE CHEMICAL SOCIETY OF JAPAN   THE SPECTROSCOPICAL SOCIETY OF JAPAN   THE SOCIETY OF JAPANESE WOMEN SCIENTISTS   JAPAN SOCIETY FOR MOLECULAR SCIENCE   

Published Papers

  • Vibrational Circular Dichroism towards Asymmetric Catalysis: Chiral Induction in Substrates Coordinated with Copper(II) Ions
    Hisako Sato, Kazuyoshi Takimoto, Jun Yoshida, Akihiko Yamagishi
    Physical Chemistry Chemical Physics DOI: 10.1039/D0CP04827E 2020/10 [Peer-reviewed]
  • Langmuir-Blodgett Films of Chiral Perfluorinated Gelators: Effects of Chirality and Chain Length on Two-dimensional Behavior
    Akihiko Yamagishi, Yasushi Umemura, Kenji Tamura, Tomoko Yajima, Hisako Sato
    Bull. Chem. Soc. Jpn. doi:10.1246/bcsj.20200245 2020/10 [Peer-reviewed]
  • Kazuyoshi Takimoto, Shinsuke Ishihara, Jan Labuta, Vaclav Brezina, Daniel Tony Payne, Jonathan P Hill, Katsuhiko Ariga, Masato Sumita, Shigeki Mori, Hisako Sato
    The journal of physical chemistry letters 11 (DOI: 10.1021/acs.jpclett.0c02284) 8464 - 8169 2020/09 [Peer-reviewed]
     Scientific journal 
    NMR spectroscopy cannot be used to discriminate enantiomers, and NMR resonances of enantiomeric mixtures are generally not affected by enantiomeric excess (ee). Here we report that a coordination complex (L·2Zn·3C), where L is a salen-like prochiral ligand and C is an exchangeable acetate co-ligand, exhibits symmetrical splitting of one of the 1H-NMR resonances of L with the degree of splitting linearly proportional to ee of the chiral guest co-ligand C, 2-phenoxypropionic acid (PPA). Despite the well-defined chirality in the crystal structure of L·2Zn·3C, concurrent fast chiral inversion and co-ligand exchange in solution renders L·2Zn·3C the primary example of prochiral solvating agent (pro-CSA) based on a coordination complex. Notably, the NMR resonances remain split even in dilute solution due to the lack of chiral guest dissociation in the co-ligand exchange system. This work provides new insights into chiral transfer events in metal-ligand complexes.
  • Visualizing helical stacking of octahedral metallomesogens with chiral core
    Go Watanabe, Hideyo Watanabe, Kota Suzuki, Hidetaka Yuge, Shintaro Yoshida, Takuyoshi Mandai, Shigetaka Yoneda, Hisako Sato, Mitsuo Hara, Jun Yoshida
    Chem. Commun. https://doi.org/10.1039/D0CC05930G 2020/09 [Peer-reviewed]
  • Hisako Sato, Izuru Kawamura
    Biochimica et Biophysica Acta - Proteins and Proteomics 1868 (8) 1570-9639 2020/08 [Peer-reviewed]
     
    © 2020 Elsevier B.V. The present article reviews the results of solid-state vibrational circular dichroism (SD-VCD) measurements on the crystals of amino acids. The investigated series were Ala, Ile, Leu, Phe, Ser, Val, and Thr. Spectra were recorded for the samples containing both D- and L-enantiomers. The molecular conformation in a crystalline state was compared among the series. Molecule optimization of their conformation under intermolecular interactions in crystalline states was revealed. One noteworthy aspect was that some VCD peaks were remarkably enhanced in comparison with the solution states. This fact was rationalized in terms of vibrationally coupled delocalization in a closely stacked pair. In addition, for a molecule with two asymmetric carbons, the signs of the VCD peaks were determined by the interplay between the two chiral centers. Lastly, the roles of the theoretical approach based on density functional theory calculations were described.
  • Izuru Kawamura, Batsaikhan Mijiddorj, Yohei Kayano, Yuta Matsuo, Yumi Ozawa, Kazuyoshi Ueda, Hisako Sato
    Biochimica et Biophysica Acta - Proteins and Proteomics 1868 (8) 1570-9639 2020/08 [Peer-reviewed]
     Scientific journal 
    © 2020 Elsevier B.V. Several D-amino acid-containing peptides (DAACPs) with antimicrobial, cardio-excitatory, or neuronal activities have been found in several species. Here, we demonstrated the chiral separation of the antimicrobial peptide diastereomers, D-phenylseptin and L-phenylseptin using (S) and (R) 3,3′-phenyl-1,1′-binaphthyl-18-crown-6-ether columns (CR-I (+) and CR-I (−), respectively) and also investigated the underlying mechanism. First, using D-amino acid-containing tripeptide Phe-Phe-Phe-OH, we found that CR-I (+) could be used to recognize diastereomeric tripeptides containing an L-amino acid as the first residue. On the contrary, CR-I (−) enabled separation of a series of diastereomers with D-amino acid as the first residue. Therefore, we achieved separation of the stereoisomers using the chiral columns depending on the position of the D- amino acid in the peptide and demonstrated the orthogonality of separations of the chiral columns. Then, using CR-I (+), we separated amphibian antimicrobial peptide diastereomers, L- and D-phenylseptin, which have the sequences, L-Phe-L-Phe-L-Phe and L-Phe-D-Phe-L-Phe at their N-termini, respectively. In order to understand the host-guest interactions, we performed molecular dynamics simulations for L-Phe-L-Phe-L-Phe tripeptide-CR-I molecule complex systems. Three hydrogen bonds between the N-terminal amine group -NH3+ and the crown ether oxygens were the dominant interactions. The hydrophobic interactions between phenyl-rings in the chiral selector unit of CR-I (+) and the side chains of 2nd and 3rd residues of the peptide also contributed to the affinity. Our results show that the CR-I (+)-column can be applied for the separation of endogenous DAACPs generated by the post-translational modification.
  • Takahiro Sakai, Yumiko Akagi, Hisashi Suzuki, Mitsuki Irie, Tetsuya Nakamura, Hisako Sato, Izuru Kawamura
    Analytical sciences : the international journal of the Japan Society for Analytical Chemistry - (-) - - - 2020/06 [Peer-reviewed]
     Scientific journal
  • Enantiomeric excess dependent splitting of NMR signal through co-ligand dynamic exchange in a coordination complex
    K. Takimoto, S. Ishihara, J. Labuta, V. B?ezina, D. T. Payne, J. P. Hill, K. Ariga, M. Sumita, S. Mori, H. Sato
    ChemRxiv https://doi.org/10.26434/chemrxiv.12198945.v1 (-) - - - 2020/04
  • Hisako Sato
    Physical Chemistry Chemical Physics 22 (15) 7671 - 7679 1463-9076 2020/04 [Peer-reviewed]
     
    This journal is © the Owner Societies. Vibrational circular dichroism (VCD) spectroscopy is an extension of circular dichroism spectroscopy into the infrared and near-infrared regions where vibrational transitions occur in the ground electronic state of a molecule. The method offers the advantage of studying the chiroptical properties of a wide range of molecules in non-crystalline states. However, because of the smallness of the signals, one measurement requires several hours to yield reliable results. Accordingly, its targets were limited to a stable molecule in a solution. To overcome this difficulty, our group applied the VCD method to supramolecular systems. The work was launched based on the finding that the VCD signal remarkably enhances when low-molecular mass gelators form gels. By analysing a number of well-resolved VCD peaks, the detailed conformation of a component molecule was deduced. This provided a clue to elucidating the molecular organization in supramolecular architectures. Our final goal was to clarify the route from microscopic molecular chirality to supramolecular chirality. For this purpose, a time-step VCD measurement method was developed for the in situ monitoring of the progress of chirality amplification.
  • Hisako Sato, Kazuyoshi Takimoto, Masaru Kato, Shin Ichi Nagaoka, Kenji Tamura, Akihiko Yamagishi
    Bulletin of the Chemical Society of Japan 93 (2) 194 - 199 0009-2673 2020/02 [Peer-reviewed]
     Scientific journal 
    © 2020 The Chemical Society of Japan. An ultrathin film was prepared by hybridizing a cationic Ir(III) complex with exfoliated nanosheets of clay minerals such as natural montmorillonite (denoted by MON) or synthetic saponite (denoted by SAP). The utilized Ir(III) complex with two long alkyl chains was [Ir(dfppy)2(dc9bpy)]+ (fppyH = 2-(2¤,4¤-difluorophenyl)pyridine; dc9bpy = 4,4¤-dinonyl-2,2¤-bi-pyridine) (denoted by DFPPY). Hybridization was performed at an air-water interface between a floating monolayer of the Ir(III) complex and the nanosheets exfoliated in an aqueous subphase. The hybrid floating film thus formed was transferred onto a hydrophilic quartz plate by a vertical dipping method. The emission from the deposited films exhibited rapid reversible change of intensity in response to the introduction or evacuation of oxygen gas in the pressure range of 0.1101.3 kPa and the temperature range from 253 K to 313 K. The lifetime of the emission decay was measured as a function of oxygen pressure, confirming the occurrence of dynamic quenching of excited Ir(III) complexes by oxygen molecules.
  • Michiya Matsusaki, Haruki Ikeguchi, Chihiro Kubo, Hisako Sato, Yuzuru Kuramochi, Daisuke Takagi
    ACS Biomaterials Science and Engineering 5 (11) 5637 - 5643 2019/11 [Peer-reviewed]
     Scientific journal 
    © 2019 American Chemical Society. Construction of three-dimensional (3D) tissues with perfusable vascular networks remains a major challenge in the field of tissue engineering. Although various sacrificial templates have been employed to fabricate the vascular networks, there are some issues with respect to cytocompatibility, structural controllability, and degradability for the achievement of precisely controlled vasculatures without cytotoxicity. Here, we demonstrate a naturally occurring polysaccharide, gellan gum (GG), as a sacrificial template material due to its unique character. GG showed rapid gelation at 30-50 °C during the cooling process depending on the concentration of bivalent calcium ions by intermolecular ionic cross-linking and subsequent double-helix formation of GG molecules. Although chelate agents such as EDTA are generally effective in decomposing ionic cross-linking gels, e.g., alginate gel, they usually show cytotoxicity. In the case of GG gel, the gels could not be decomposed by the chelate agents but were easily decomposed by Tris-HCl buffer (pH = 7.4), which is a basic molecule with high cytocompatibility. We finally fabricated straight vascular tubes in 3D-gelatin gels and then demonstrated perfusion of human whole blood at 3.0 cm/s for 2 h. Since the complex vascular networks were constructed by 3D inkjet printing of the GG solution, GG would be useful as a structurally controllable and easily decomposable sacrificial material with cytocompatibility.
  • Hisako Sato, Kazuyoshi Takimoto, Izuru Kawamura, Sumio Aisawa
    Bull. Chem. Soc. Jpn. 92 1779 - 1784 0009-2673 2019/10 [Peer-reviewed]
     
    © 2019 The Chemical Society of Japan Solid-state vibrational circular dichroism (SD-VCD) spectra were measured for the intercalation compounds of layered double hydroxide (LDH) and D- or L-phenylalanine (D- or L-Phe). The investigated LDH was composed of Zn(II) and Al(III) in 2:1 molar ratio. For comparison, the SD-VCD spectra were recorded for enantiopure crystalline samples of Phe. The measured spectra were analyzed with the help of a theoretical simulation calculated by the Gaussian16 program. It was concluded that Phe formed a tetramer in the crystalline state, forming intermolecular hydrogen bonds between COO1 and NH3+ groups. In the intercalated states, the neighboring Phe molecules oriented vertically to the layer surface in an anti-parallel fashion, forming their COO1 groups hydrogen bonded individually with the OH groups on the surface of LDH. The results demonstrated the utility of the SD-VCD method for obtaining the detailed conformation of a molecule within an inorganic host.
  • Izuru Kawamura, Hisako Sato
    Analytical Biochemistry 580 14 - 20 0003-2697 2019/09 [Peer-reviewed]
     Scientific journal 
    © 2019 Elsevier Inc. D-Serine is considered a key endogenous substance involved in several enzymatic reactions in the human body. In this study, solid-state vibrational circular dichroism (VCD) measurements of enantiomeric serine were performed for spectroscopic distinction between D- and L-serine. The mirror-image VCD signals of the isomers in the KBr pellets were observed in the mid-infrared range of 1800–1250 cm−1. The calculated infrared (IR) and VCD spectra for the optimized serine structures were in good agreement with the corresponding observed spectra. In addition, the chemical shift values estimated from the shielding constants of the optimized structure of serine corresponded with the observed values in 13C and 15N solid-state nuclear magnetic resonance spectra, supporting the VCD assignments. Our results suggest the need for further study of VCD to develop a sensitive and high-resolution spectroscopic technique for the detection of D-amino acids.
  • Batsaikhan Mijiddorj, Yuta Matsuo, Hisako Sato, Kazuyoshi Ueda, Izuru Kawamura
    Applied Sciences (Switzerland) 9 (13) 2601  2019/07 [Peer-reviewed]
     
    © 2019 by the authors. L-phenylseptin (L-Phes) and D-phenylseptin (D-Phes) are amphibian antimicrobial peptides isolated from the skin secretion of Hypsiboas punctatus. In the N-termini, L-Phes and D-Phes contain three consecutive phenylalanine residues, L-Phe-L-Phe-L-Phe and L-Phe-D-Phe-L-Phe, respectively. They are known to exhibit antimicrobial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Xanthomonas axonopodis pv. Glycines. However, their mechanism of action and the role of the D-amino acid residue have not been elucidated yet. In this study, the interactions of both peptides with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) were investigated by means of quartz crystal microbalance, circular dichroism, vibrational circular dichroism, 31P solid-state NMR, and molecular dynamics simulation. Both peptides have similar binding constants to the DMPC lipid bilayers, in the order of 106 M-1, and form an α-helix structure in the DMPC lipid bilayers. Both the peptides induce similar changes in the dynamics of DMPC lipids. Thus, in spite of the difference in the conformations caused by the chirality at the N-terminus, the peptides showed similar behavior in the membrane-bound state, experimentally and computationally.
  • 川村出, 川村出, BATSAIKHAN Mijiddorj, BATSAIKHAN Mijiddorj, 大山暁史, 佐藤久子
    生化学 91 (3) 316‐321  0037-1017 2019/06 [Invited]
  • 森田昌敏, 山岸晧彦, 山岸晧彦, 山下浩, 佐藤久子
    環境放射能除染学会誌 7 (2) 115‐122  2187-8382 2019/06 [Peer-reviewed]
  • Yumi Ozawa, Hisako Sato, Yohei Kayano, Nana Yamaki, Yu-ichiro Izato, Atsumi Miyake, Akira Naito, Izuru Kawamura
    PHYSICAL CHEMISTRY CHEMICAL PHYSICS 21 (21) 10879 - 10883 1463-9076 2019/06 [Peer-reviewed]
     Scientific journal 
    Self-assembling phenylalanine-based peptides have garnered interest owing to their potential for creating new functional materials. Here, we designed four diastereomers, L-Phe-L-Phe-L-Phe (FFF), D-Phe-LPhe- L-Phe (fFF), L-Phe-D-Phe-L-Phe (FfF) and L-Phe-L-Phe-D-Phe (FFf), to analyze the effect of the D-isomer on the self-assembly. Using SEM, TG, VCD, and solid-state NMR measurements, we found that only FFf forms a c-turn conformation and self-assembles into a nanoplate with higher thermal stability. The supramolecular structure of FFf consists of intra-and intermolecular hydrogen bonds and p-p stackings. From our results, we have discovered that FFf forms a new type of self-assembling c-turn conformation, clarifying the structural role of a D-amino acid residue in supramolecular formation.
  • Toshiyuki Sasaki, Toshiyuki Sasaki, Mikiji Miyata, Seiji Tsuzuki, Hisako Sato
    Crystal Growth and Design 19 1411 - 1417 1528-7483 2019/02 [Peer-reviewed]
     Scientific journal 
    Copyright © 2019 American Chemical Society. Controlling chiral crystallization, which remains one of the biggest challenges in crystal engineering, brings enormous advantages in material sciences, especially chiral industries. This work demonstrates that chiral crystallization is controllable by designing structures of 2-fold helices, which affect the manner of interhelical interactions. Here we show an example of chiral crystallization by using achiral primary ammonium carboxylates having simple chemical structures: naphthyl and tert-butyl groups. Their crystal structures were precisely investigated by focusing on hydrogen-bonded 2-fold helices along with theoretical calculations. Consequently, a key role of interhelical CH/π contacts in chiral crystallization was found to be not attracting but arranging chiral 2-fold helices. More importantly, a clear difference was found in densities of 2-fold helices and their stacking between chiral and achiral crystals.
  • Yutaro Goto, Yutaka Watanabe, Aoki Noboriguchi, Jun Yoshida, Shigeki Mori, Hisako Sato
    Dalton Transactions 48 (27) 10138 - 10144 1477-9226 2019 [Peer-reviewed]
     Scientific journal 
    © 2019 The Royal Society of Chemistry. An approach of molecular tectonics was applied to synthesize a tetranuclear Pd(ii) complex with axial chirality, [{(Lt)Pd(ii)(taet)Pd(ii)}2(tpret)] (LtH = benzoylacetone (bzacH) or 2-naphthoylacetone (npacH), taetH2 = 1,1,2,2-tetraacetylethane and tpretH2 = 1,1,2,2-tetrapropanoylethane). As a first step, a two-handed tecton, [{taetH}Pd(ii)]2(tpret)], was synthesized. Next monomeric Pd(ii) units were connected to both ends of the tecton to form a reactive tetranuclear intermediate, [{(hfac)Pd(ii)(taet)Pd(ii)}2(tpret)] (hfacH = hexafluoroacetylacetone). Finally terminal hfac groups were replaced with the β-diketonato ligands having one or two bulky groups such as dibenzoylmethane (dbmH), bzacH and npacH. In the case of the symmetrically substituted ligand (dbm), the formed complex was achiral and its structure was determined by single crystal X-ray analysis. In the case of unsymmetrical ligands (bzac and npac), the complexes were axially chiral due to the vertical twisting of the terminal ligands. The complexes were optically resolved chromatographically on a chiral column. Their chiro-optical properties were investigated by means of electronic (ECD) and vibrational circular dichroism (VCD) spectroscopy. Notably the twisting relation between the two terminal ligands of the tetranuclear complexes influenced significantly chiral electronic properties, although they were separated by a distance longer than 3 nm.
  • Hisako Sato, Keisuke Watanabe, Jun Koshoubu
    Chem.Lett. 47 (-) 1435 - 1437 0366-7022 2018/11 [Peer-reviewed]
     Scientific journal
  • Ryotaro Ozaki, Tatsuya Yamada, Shinji Yudate, Kazunori Kadowaki, Hisako Sato
    Sci. Rep. 8 (-) DOI:10.1038/s41598-018-35467-4 - 17119 2018/11 [Peer-reviewed]
     Scientific journal
  • Jun Yoshida, Syuhei Tamura, Keisuke Hoshino, Hidetaka Yuge, Hisako Sato, Akane Yamazaki, Shigetaka Yoneda, Go Watanabe
    JOURNAL OF PHYSICAL CHEMISTRY B 122 (46) 10615 - 10626 1520-6106 2018/11 [Peer-reviewed]
     Scientific journal 
    Nematic liquid crystals (LCs) are known to transform into chiral nematic LCs with helical structures upon doping with enantiomeric compounds (called chiral dopants or guests). Here, we investigated the mechanism of host LC- and guest-dependent helix inversion by using octahedral metal complexes as guests. The helical twisting powers (HTPs/mu m(-1)) of eight metal complexes with Delta, Lambda chirality were examined in five nematic LC hosts. For example, Delta-[Ru(acac)(2)(trop)] (Ru-trop, Hacac = 2,4-pentanedione, Htrop = tropolone) induces a left-handed (M) helix upon doping with N-(4-methoxybenzylidene)-4-butylaniline (MBBA), whereas it induces an opposite right-handed (P) helix in 4-cyano-4'-pentylbiphenyl (5CB). The monobrominated complex of Ru-trop, Delta-[Ru(acac)(2)(Brtrop)] (Ru-Br(1)trop, HBr(1)trop = 5-bromotropolone), induces P helices in both MBBA and 5CB, whereas the dibrominated complex, Delta-[Ru(acac)(2)(Br(2)trop)] (Ru-Br(2)trop, HBr(2)trop = 3,7-dibromotroplone) induces M helices in both the media. The molecular dynamics simulation performed in parallel confirmed the drastic effect of the bromo groups on the microscopic ordering direction of guests in nematics. Further, HTPs of all Delta isomers of metal complexes investigated were found to shift in the positive direction as the dielectric constant anisotropy (Delta epsilon) of the host LCs increases (and vice versa for Lambda isomers). These experimental and calculated results highlight the interplay of steric (excluded volume effect) and electrostatic (dipole-dielectric body) interactions between the host LCs and guest metal complexes.
  • Tomohiko Okada, Mutsuki Oguri, Kazuki Tajima, Tomohiko Yamakami, Hisako Sato
    Applied Clay Science 163 72 - 80 0169-1317 2018/10 [Peer-reviewed]
     Scientific journal 
    © 2018 The proposed study aims to prepare clay-coated spherical silica particles to be applied as a column packing material for chiral high performance liquid chromatography (HPLC). These particles were prepared by directly growing a hectorite-like layered silicate on porous and non-porous amorphous silica. The direct crystallization of the layered silicate was performed using the reactions of lithium fluoride, magnesium chloride, and silica in the presence of urea under hydrothermal conditions (373 K for 2 d) and led to a homogeneous coverage on the silica surfaces within a 0.4 μm thickness of the aggregates. The resulting layered silicate involved full ion-exchange reactions with an enantiomeric Δ-tris(1,10-phenanthroline)ruthenium(II). The organically modified particles packed into a stainless steel tube optically resolved a racemic mixture of tris(acetylacetonato)ruthenium(II) in a flow of methanol. The resolution efficiency determined by the retention time and full width at half maximum was influenced by the crystalline size and could be adjusted using different porosities of the initial silica and by varying the quantities of added Li and Mg ions to the starting mixtures. Fine platy crystals and their thin layer aggregates on the porous silica contributed toward the good resolution efficiency and a reduction in the elution volume owing to the rapid diffusion of the racemic mixture into the layered silicate.
  • Sato H, Takimoto K, Mori H, Yamagishi A
    Physical chemistry chemical physics : PCCP 20 (39) 25421 - 25427 1463-9076 2018/10 [Peer-reviewed]
  • Hisako SATO, Hiroshi YAMASHITA, Daisuke OOMORI, Kenji TAMURA, Yoshiro KANEKO, Akihiko YAMAGISHI, Masatoshi MORITA
    環境放射能除染学会誌 6 (3) 153 - 161 2187-8382 2018/09 [Peer-reviewed][Invited]
     Scientific journal
  • Hisako Sato, Fumi Sato, Akihiko Yamagishi
    Inorganics 6 2018/09 [Peer-reviewed][Invited]
     
    © 2018 by the authors. The present article reports the application of vibrational circular dichroism (VCD) and temperature-dependent electronic circular dichroism (ECD) methods to reveal the dynamical aspects of a star-burst tetranuclear metal complex with a labile central core in a solution. One-handed chiral inert tecton, Δ- or Λ-[Ru(III)(acac)2(taetH)] (acacH = acetylacetone, taetH2 = tetraacetylethane), was prepared by reacting [Ru(acac)3] with taetH2 in solid at 120 °C. The ΔΛ-pair of pure enantiomers was obtained chromatographically. On adding Al(ClO4)3 to its enantiopure solution, three units of one-handed tecton were assembled spontaneously around an aluminum(III) ion to form a star-burst tetranuclear complex, [{Δ- or Λ-Ru(acac)2(taet)}3Al(III)]. The VCD spectrum recorded on the CDCl3 solution of the complex showed that the central chirality around an Al(III) ion took dominantly the absolute configuration antipodal to those of peripheral Ru(III) units at the temperature lower than -10 °C. The complex underwent interconversion between the Δ- and Λ-configurations around a central Al(III) core (or epimerization) in solution. The activation energy barrier was determined from the time courses of ECD spectra in CHCl3 and CH3OH.
  • Toshiyuki Sasaki, Toshiyuki Sasaki, Mikiji Miyata, Hisako Sato
    Crystal Growth and Design 18 4621 - 4627 1528-7483 2018/08 [Peer-reviewed]
     Scientific journal 
    © Copyright 2018 American Chemical Society. The applicability of advanced graph set analysis and solid-state vibrational circular dichroism (SD-VCD) spectroscopy to the characterization of supramolecular chirality has been demonstrated. Recrystallization of R-(+)-1-phenylethylammonium 1-naphthoate affords two polymorphic crystals: one is composed of hydrogen-bonded (HB) 2-fold helices with helicity, while the other contains HB clusters with topological chirality. Handedness and origins of the chirality were crystallographically characterized by advanced graph set analysis. SD-VCD measurements were then recorded for these polymorphic crystals using the VCD spectrometer PRESTO-S-2007, which we developed. Unique VCD spectra were observed because of the difference in features of the chiral supramolecular structures. Enhancement of VCD signals depending on dimensionality of the supermolecules is especially noteworthy. Generality of 2-fold helices, demonstrated by statistics from the Cambridge Structural Database, and geometrical characteristics and theoretical simplicity of the HB clusters, because of their finite number of components connected by closed-hydrogen bonding networks, allowed them to become reasonable representative examples for chiral supermolecules.
  • Batsaikhan Mijiddorj, Shiho Kaneda, Hisako Sato, Yuki Kitahashi, Namsrai Javkhlantugs, Akira Naito, Kazuyoshi Ueda, Izuru Kawamura
    Biochimica et Biophysica Acta - Proteins and Proteomics 1866 (7) 789 - 798 1878-1454 2018/07 [Peer-reviewed]
     Scientific journal 
    Bombinin H4 is an antimicrobial peptide that was isolated from the toad Bombina variegata. Bombinin H family peptides are active against gram-positive, gram-negative bacteria, and fungi as well as the parasite Leishmania. Among them, bombinin H4 (H4), which contains D-allo-isoleucine (D-allo-Ile) as the second residue in its sequence, is the most active, and its L-isomer is bombinin H2 (H2). H4 has a significantly lower LC50 than H2 against Leishmania. However, the atomic-level mechanism of the membrane interaction and higher activity of H4 has not been clarified. In this work, we investigated the behavior of the conformations and interactions of H2 and H4 with the Leishmania membrane using 31P solid-state nuclear magnetic resonance (NMR), vibrational circular dichroism (VCD) spectroscopy, and molecular dynamics (MD) simulations. The generation of isotropic 31P NMR signals depending on the peptide concentration indicated the abilities of H2 and H4 to exert antimicrobial activity via membrane disruption. The VCD experiment and density functional theory calculation confirmed the different stability and conformations of the N-termini of H2 and H4. MD simulations revealed that the N-terminus of H4 is more stable than that of H2 in the membrane, in line with the VCD experiment data. VCD and MD analyses demonstrated that the first L-Ile and second D-allo-Ile of H4 tend to take a cis conformation. These residues function as an anchor and facilitate the easy winding of the helical conformation of H4 in the membrane. It may assist to quickly reach to the threshold concentration of H4 on the Leishmania membrane. This article is part of a Special Issue entitled: D-Amino acids: biology in the mirror, edited by Dr. Loredano Pollegioni, Dr. Jean-Pierre Mothet and Dr. Molla Gianluca.
  • Toshiyuki Sasaki, Akiko Egami, Tomoko Yajima, Hidehiro Uekusa, Hisako Sato
    Crystal Growth and Design 18 4200 - 4205 1528-7483 2018/07 [Peer-reviewed]
     Scientific journal 
    Copyright © 2018 American Chemical Society. Gels composed of low molecular weight gelators (LMWGs) are fascinating research targets from the viewpoint of applications because their functionalities are easily modified by designing their molecular structures. Some reliable gelator design approaches have been developed. However, new classes of molecular gelators are sometimes discovered unexpectedly, suggesting that there remain unknown aspects about gelators. To obtain knowledge regarding gelation and crystallization ability, the crystal structure of N,N′-diperfluorooctanoyl-(1R,2R)-1,2-diaminocyclohexane (RR-CF8), which is a derivative of 1,2-diaminocyclohexane, one of the most famous LMWGs, was investigated in addition to the vibrational circular dichroism (VCD) measurements. The crystal structure was solved from powder X-ray diffraction patterns because recrystallization of RR-CF8 afforded no suitable single crystals for single crystal X-ray diffraction measurement. Two unusual structural features were confirmed. One is that the perfluoroalkyl chain (PFC) of RR-CF8 forms a pseudoracemic helix, or a mixture of right- (P) and left-handed (M) helices, while elsewhere, PFCs generally have one-handed helicity. The other is that an oxygen atom of one of the amide groups is free of hydrogen bonds, reducing the stability of one-dimensional hydrogen-bonded assemblies. These unique structural features let us propose the reasonable explanations for the gelation and crystallization ability of RR-CF8. Furthermore, a factor of environment-dependent chirality inversion of RR-CF8 supermolecules was clarified by combining X-ray crystallography and solid-state VCD spectroscopy.
  • Shinsuke Ishihara, Jan Labuta, Zdeněk Futera, Shigeki Mori, Hisako Sato, Katsuhiko Ariga, Jonathan P Hill
    The journal of physical chemistry. B 122 (19) 5114 - 5120 1520-6106 2018/05 [Peer-reviewed]
     Scientific journal 
    The use of chiral auxiliaries, which derivatize enantiomers to diastereomers, is an established technique for NMR spectroscopic analysis of chirality and enantiomeric excess ( ee). Here we report that some small prochiral molecules exhibit ee-dependent splitting of 1H NMR signals at room temperature based on acid/base interactions with chiral analytes, especially when either a chiral or prochiral acid contains a phenoxy group at the α-position of the carboxylic acid. As a representative case, the benzylamine (BA)/2-phenoxylpropionic acid (PPA) complex was comprehensively investigated by using various methods. Notably, X-ray crystallographic analysis shows that there are multipoint interactions in the BA/PPA complex, implying that "fixing" of molecular conformation is critical for efficient intermolecular transfer of magnetic anisotropy. Our results suggest that a wide range of prochiral molecules are available for NMR determination of ee when intermolecular interactions between prochiral molecules and chiral analytes are adequately designed.
  • Mijiddorj B, Kaneda S, Sato H, Kitahashi Y, Javkhlantugs N, Naito A, Ueda K, Kawamura I
    Biochimica et biophysica acta 1866 (7) 789 - 798 0006-3002 2018/05 [Peer-reviewed]
  • Hyesong Park, Ka Young Kim, Sung Ho Jung, Yeonweon Choi, Hisako Sato, Jong Hwa Jung
    Chemistry of Materials 30 (6) 2074 - 2083 1520-5002 2018/03 [Peer-reviewed]
     Scientific journal 
    We report a distinctly different dynamic helix inversion pathway of self-assembled terpyridine-based ligands composed of different numbers of peptide moieties with Co2+ and its amplification of strain-induced chirality from an achiral terpyridine moiety. The helical chirality of the metal centers, coordinated by terpyridine ligands, is controlled by strain-induced chirality with complex ligand-to-Co2+ ratios. We also show that the distinct helical inversion mechanism is significantly dependent on the number of peptides attached to ligands. The helical inversion pathway of the self-assembled ligand (R-1 and S-1) complexes composed of one alanine analogue (R- or S-2-amino-1-propyl moiety) and one long saturated alkyl chain relies on two steps of chirality with different complex geometries, first from strain-induced chirality originating from an octahedral structure to octahedral structure with different helical direction and then on to helical chirality in a square-pyramidal structure. In contrast, the helix inversion of the self-assembled R-2 and S-2 complexes containing an alanine analogue and two glycine moieties with Co2+ was followed by one step to form two distinct coexisting complex geometries having the same helical direction. In particular, the circular dichroism (CD) intensities of the self-assembled R-1 and R-2 complexes with Co2+ were 900-1500-fold amplified compared to those of free R-1 and R-2. The Gibbs free energies of the self-assembled complexes with different geometries were also calculated by temperature-dependent CD observation the square-pyramidal structure of the self-assembled R-1 complex with Co2+ was more stable than the self-assembled R-2 complex with Co2+. Furthermore, the self-assembled R-1 and S-1 complexes with 1.0 equiv of Co2+ could classify amino acids by their chirality.
  • Ryotaro Ozaki, Tetsuya Yamada, Shinji Yudate, Kazunori Kadowaki, Hisako Sato
    Japanese Journal of Applied Physics 57 (3) 1347-4065 2018/03 [Peer-reviewed]
     International conference proceedings 
    Cyclometalated Ir(III) complexes are attracting extensive attention due to their high emission properties in the visible region. Oxygen sensitive photoluminescence (PL) emissions from single- and multi-layered Ir(III) Langmuir-Blodgett (LB) films are measured. The single-layered LB film on a non-aluminum coated glass substrate shows oxygen sensitive PL emission but its intensity is very weak. In contrast, the multi-layered LB film shows higher intensity but their oxygen sensitivity is lower than that of the single-layered sample. To break the trade-off between intensity and sensitivity, PL characteristics from the LB film on an aluminum-coated glass substrate are investigated. The PL emission from the LB film on the metal layer show higher intensity and good oxygen sensitivity. The mechanism of the emission enhancement is also discussed in this paper.
  • Masaru Kato, Hisako Sato, Ichizo Yagi, Miwa Sugiura
    Electrochimica Acta 264 386 - 392 0013-4686 2018/02 [Peer-reviewed]
     Scientific journal 
    Photosynthesis converts solar energy into chemical energy. Photosystem II (PSII) oxidizes water to produce oxygen, electrons and protons under solar light irradiation. This light-driven water oxidation initiates a series of reactions in photosynthesis. Basic photoelectrochemical studies on PSII are directed toward the enzymatic applications of PSII for sustainable production of electricity or solar fuels. To maximize the photoelectrochemical catalytic activity of PSII on electrode substrates, interfacial designs between PSII and electrode substrates are important. Herein, we report bio-inorganic photoanodes of PSII and ferricyanide-intercalated layered double hydroxide (LDH) for visible-light-driven water oxidation. PSII is simply drop-cast onto a ferricyanide-intercalated cobalt–aluminum LDH and then shows a turnover frequency of 0.5 ± 0.1 s−1 and a turnover number of 920 ± 40 for 1 h at pH 6.5 at +0.5 V vs. NHE under visible light irradiation. Photoelectrochemical experiments using a PSII inhibitor or a bio-engineered PSII suggest that interfacial electron transfer from the plastoquinone QA site of PSII to ferricyanide may play an important role in improving the photo-electrocatalytic activity and stability of PSII. Our studies will open up new possibilities in fundamental or advanced photoelectrochemical studies of PSII.
  • Hisako Sato, Kenji Tamura, Kazuyoshi Takimoto, Akihiko Yamagishi
    Physical Chemistry Chemical Physics 20 (5) 3141 - 3147 1463-9076 2018/02 [Peer-reviewed]
     Scientific journal 
    Vibrational circular dichroism (VCD) spectroscopy was applied to study chirality recognition in the interlayer space of a clay mineral. Clay intercalation compounds including two kinds of chiral molecules were prepared. Firstly a cationic metal complex, Δ- or Λ-[Ru(phen)3]2+ (phen = 1,10-phenanthroline), was ion-exchanged into sodium montmorillonite. Thereafter a neutral organic molecule, R- or S-1,1′-bi-2-naphthol (denoted as R- or S-BINOL), was co-adsorbed. The solid state VCD spectra were recorded on the hybrid compounds thus prepared. The intensity of VCD peaks in the region of 1300-1400 cm-1, which were assigned to the bending vibrations of OH groups in BINOL, was remarkably dependent on the chirality relation between the two intercalated species. This implied that BINOL took a different conformation in response to the chirality of co-existing [Ru(phen)3]2+.
  • Hisako Sato, Tomoko Yajima, Akihiko Yamagishi
    Physical Chemistry Chemical Physics 20 (5) 3210 - 3215 1463-9076 2018/02 [Peer-reviewed]
     Scientific journal 
    A mixture of chiral low-molecular weight gelators, (1R,2R)- or (1S,2S)-N,N′-diperfluoroheptanoyl-1,2-diaminocyclohexane (denoted as RR- or SS-CF7, respectively) and (1R,2R)- or (1S,2S)-N,N′-diheptanoyl-1,2-diaminocyclohexane (denoted as RR- or SS-CH7, respectively), was used as a two-component gelator in acetonitrile solvent. The process of gelation was investigated by time-step vibrational circular dichroism (VCD) spectroscopy. The method enabled us to study the dynamical behavior of CF7 and CH7 molecules independent of their characteristic vibrational bands. We focused on the effects of the chirality relation between the two gelators. In the case of the enantiomeric mixtures (RR-CF7/RR-CH7 or SS-CF7/SS-CH7), the two components exhibited different time-courses in their VCD spectra. As for CF7, the couplet peak intensities assigned to CO stretching increased with time, while those for CH7 remained low. In the case of the racemic mixture (RR-CF7/SS-CH7 or SS-CF7/RR-CH7), the intensities of the peaks assigned to the CO stretching vibration for both CF7 and CH7 molecules maintained a constant level with time. The VCD results were compared with the SEM images of the freeze-dried gel samples taken at various time intervals. Furthermore, the mechanisms for the gelation of two-component systems are discussed.
  • Kazuyoshi Takimoto, Kenji Tamura, Yutaka Watanabe, Akihiko Yamagishi, Hisako Sato
    New Journal of Chemistry 42 (7) 4818 - 4823 1369-9261 2018 [Peer-reviewed]
     Scientific journal 
    An attempt to develop a chiral luminescent probe with enantioselectivity is described. A tris(chelated) iridium(iii) complex with bulky ligands, [Ir(bzq)2(phen)]+ (bzqH = benzo[h]quinoline phen = 1,10-phenanthroline), was synthesized and optically resolved into Δ- and Λ-enantiomers. The complex (denoted as Ir(iii)) was emissive in non-polar organic solvents, while in aprotic and protic polar solvents it was less emissive. When Ir(iii) was adsorbed by the colloidal particles of synthetic saponite (denoted as SAP), it recovered its emitting capability even in a solvent containing water. Emission from Ir(iii) adsorbed by SAP was quenched by adding [Ru(acac)3] (acac = acetylacetonato, denoted as Ru(iii)). The Stern-Volmer constant (KSV) exhibited remarkable stereoselectivity KSV = 15:900 ± 900 M-1 for Δ-Ir(iii)/Δ-[Ru(acac)3] (or Λ-Ir(Iiii)/Λ-[Ru(acac)3]) and 7000 ± 500 M-1 for Δ-Ir(iii)/Λ-[Ru(acac)3] (or Λ-Ir(iii)/Δ-[Ru(acac)3]). The dependence of the emission lifetime on the concentration of Ru(iii) indicated that quenching proceeded dynamically. On the basis of the molecular model, it was postulated that a microscopic pocket surrounded by the bulky ligands at the top of adsorbed Ir(iii) acted as a site discriminating the chirality of an approaching molecule.
  • Hajime Torii, Hisako Sato
    Physical Chemistry Chemical Physics 20 (22) 14992 - 14996 1463-9076 2018 [Peer-reviewed]
     Scientific journal 
    Chiro-optical spectroscopic methods, such as vibrational circular dichroism (VCD) spectroscopy, are regarded as useful measures that provide us information on the structural properties of chiral species, but for correct interpretation of the measured spectra, appropriate modeling that can be compared with the observed spectra is essential. In the present study, the origin of the VCD intensity enhancement observed upon fibril formation in a gelation process is examined theoretically. Comparing with the observed spectroscopic feature and also with the observed scanning electron microscope (SEM) image, it is derived that there are at least three hierarchical tiers of chirality in the gel. The VCD intensity enhancement originates from one of them on the ∼50 nm length scale, which consists of a co-axial antiparallel right-handed double helical structure that persistently continues over ∼100 molecules, indicating that the intermediate length-scale fibril formation plays a crucial role in the VCD intensity enhancement, in a way similar to some fibril-forming peptides examined previously. The time course of the gelation process observed by the time dependence of the VCD intensity is also shown and discussed.
  • Hisako Sato, Kenji Tamura, Akihiko Yamagishi
    Chemosensors 5 (4) 2227-9040 2017/12 [Peer-reviewed]
     Scientific journal 
    An ultra-thin hybrid film of amphiphilic iridium(III) complexes and synthetic saponite was manipulated by means of the modified Langmuir-Blodgett method. In the film deposited onto a quartz substrate, the external mixed molecular layer of amphiphilic iridium(III) complexes was reinforced by the inner layer of exfoliated synthetic saponite. As components of the molecular layer, two iridium(III) complexes were used: [Ir(dfppy)2(dc9bpy)]+ (dfppyH = 2-(4',6'-difluorophenyl) pyridine dc9bpy = 4,4'-dinonyl-2,2'-bipyridine) (denoted as DFPPY) and [Ir(piq)2(dc9bpy)]+ (piqH = 1-phenyisoquinoline)) denoted as PIQ). The emission spectra from the films changed from blue to red maxima with the decrease of a ratio of DFPPY/PIQ due to the energy transfer from excited DFPPY to PIQ. The intensity of red decreased with the increase of oxygen pressure through the quenching of excited iridium(III) complexes, promising a possibility as an oxygen-sensing film.
  • Akihiko Yamagishi, Kenji Tamura, Tomoko Yajima, Hisako Sato
    CHEMISTRY LETTERS 46 (11) 1679 - 1682 0366-7022 2017/09 [Peer-reviewed]
     Scientific journal 
    The monolayer behavior of a chiral gelator with perfluoroalkyl chains, (1R,2R)- or (1S,2S)-N,N'-diperfluoroheptanoyl-1,2-diaminocyclohexane (denoted as RR-or SS-CF7, respectively), was investigated by means of the Langmuir-Blodgett method. The AFM image of an enantiomeric film deposited onto a hydrophilic glass plate exhibited an array of rod-like aggregates with 0.05-0.8 mu m in diameter, suggesting that they were a twodimensional analogue of fibrils in a gel.
  • Hisako Sato, Izuru Kawamura, Akihiko Yamagishi, Fumi Sato
    CHEMISTRY LETTERS 46 (4) 449 - 452 0366-7022 2017/04 [Peer-reviewed]
     Scientific journal 
    The solid-state vibrational circular dichroism spectra were measured for isoleucine and its related compounds. These amino acids are characterized by the presence of two chiral centers (the asymmetric carbon in an alkyl chain and the one at the alpha-position). The couplet peaks were observed for the stretching vibrations of -COOH and the bending vibration of -NH2. The signs of the peaks due to -COOH were determined uniquely by the RS-chirality of the alpha-carbon, while those due to -NH2 were dependent on the combination of the chirality of the alpha-carbon and the carbon in an alkyl chain. The results implied that the asymmetric vibrational behavior of an -NH2 group was affected by the interplay between two chiral centers.
  • Hisako Sato, Kenji Tamura, Tomoko Yajima, Fumi Sato, Akihiko Yamagishi
    NEW JOURNAL OF CHEMISTRY 41 (7) 2780 - 2785 1144-0546 2017/04 [Peer-reviewed]
     Scientific journal 
    An attempt of developing a chiral luminescent probe for amino acids was described. Two types of chiral iridium(III) complexes were synthesized: [Ir(dfppy)(2)(R-pep-bpy)](+) (dfppyH = 2-(2',4'-difluorophenyl)pyridine); R-pep-bpy = 4,4'-bis((R-1,2-dimethylpropyl)aminocarbonyl-2,2'-bipyridine) and [Ir(piq)(2)(R-pep-bpy)](+) (piqH = 1-phenyisoquinoline). In both complexes, amido groups (R-pep-) were attached to 2,2'-bipyridine with an intension of increasing the affinity for an amino acid. The complexes were optically resolved on a chiral column. When the complexes were adsorbed by the colloidal particles of synthetic saponite, they were highly emissive even in a medium containing water. The remarkable quenching of emission was observed for the combination of [Ir(dfppy)(2)(R-pep-bpy)](+) and tryptophan methyl ester. By the use of the enantiomeric complexes, the possibility of enantioselective quenching was examined for various amino acid derivatives.
  • Hisako Sato, Izuru Kawamura, Akihiko Yamagishi, Fumi Sato
    Chemistry Letters 46 (4) 449 - 452 1348-0715 2017 [Peer-reviewed]
     Scientific journal 
    The solid-state vibrational circular dichroism spectra were measured for isoleucine and its related compounds. These amino acids are characterized by the presence of two chiral centers (the asymmetric carbon in an alkyl chain and the one at the α-position). The couplet peaks were observed for the stretching vibrations of -COOH and the bending vibration of -NH2. The signs of the peaks due to -COOH were determined uniquely by the RS-chirality of the α-carbon, while those due to -NH2 were dependent on the combination of the chirality of the α-carbon and the carbon in an alkyl chain. The results implied that the asymmetric vibrational behavior of an -NH2 group was affected by the interplay between two chiral centers.
  • Kazuyoshi Takimoto, Yutaka Watanabe, Shigeki Mori, Hisako Sato
    Dalton Transactions 46 (13) 4397 - 4402 1477-9226 2017 [Peer-reviewed]
     Scientific journal 
    © The Royal Society of Chemistry. Vibrational circular dichroism (VCD) spectra are measured for dichloromethane solutions of the resolved enantiomers of [Ir(bzq)2(phen)]+ (bzqH = benzo[h]quinoline; phen = 1,10-phenanthroline). The absolute configuration of each enantiomer is determined by comparing the experimental and theoretical spectra. The result is in accord with the results of the X-ray single crystallographic analysis on the enantiomeric crystal. Moreover, the importance of the CH-π interaction is derived between phen and a hydrogen atom in bzq in the molecular packing of both the enantiomeric and racemic crystals. A helical column is formed in the enantiomeric crystal in the tetragonal space group P43, whereas a tight racemic pair is formed in the racemic crystal in the monoclinic space group P21/n.
  • Tomohiko Okada, Aisaku Kumasaki, Kei Shimizu, Akihiko Yamagishi, Hisako Sato
    JOURNAL OF CHROMATOGRAPHIC SCIENCE 54 (7) 1238 - 1243 0021-9665 2016/08 [Peer-reviewed]
     Scientific journal 
    A new type of clay column particles was prepared, in which a hectorite layer (similar to 0.1 mu m thickness) covered uniformly the surface of amorphous silica particles with an average radius of 5 mu m (ref. Okada et al., The Journal of Physical Chemistry C, 116, 21864-21869 (2012)). The hectorite layer was fully ion-exchanged with Delta-[Ru(phen)(3)](2+) (phen = 1,10-phenanthroline) ions by being immersed in a methanol solution of Delta-[Ru(phen)(3)](ClO4)(2) (1 mM). The modified silica gel particles thus prepared were packed into a stainless steel tube (4 mm (i.d.) x 25 cm) as a high-performance liquid chromatography column. Optical resolution was achieved when the racemic mixtures of several metal complexes or organic molecules were eluted with methanol. In the case of tris(acetylacetonato) ruthenium(III) ([Ru(acac)(3)]), for example, the Lambda- and Delta-enantiomers gave an elution volume of 2.6 and 3.0 mL, respectively, with the separation factor of 1.2. The total elution volume (5 mL) was nearly one-tenth for the previously reported column of the same size (RU-1 (Shiseido Co., Ltd.)) packed with the spray-dried particles of synthetic hectorite (average radius 5 mu m) ion-exchanged by the same Ru(II) complexes.
  • Kazuko Fujii, Shigenobu Hayashi, Hideo Hashizume, Shuichi Shimomura, Keiko Jimura, Taketoshi Fujita, Nobuo Iyi, Akihiko Yamagishi, Hisako Sato, Toshihiro Ando
    PHYSICAL CHEMISTRY CHEMICAL PHYSICS 18 (28) 19146 - 19157 1463-9076 2016/07 [Peer-reviewed]
     Scientific journal 
    Through various in situ analyses, we have revealed the structural changes that occur during the reversible melting-solidification process of layered alkylsiloxanes (C(n)LSiloxanes) with carbon numbers (n) of 18 and 16. In situ high-resolution solid-state C-13 nuclear magnetic resonance (NMR) analysis at controlled temperatures indicates drastic conformational changes of the long alkyl chains during the melting-solidification process. A C-13 NMR signal at 33 ppm, which shows the highest intensity at room temperature (RT), is assigned to an inner methylene group with an all-trans conformation. As the temperature increases, the 33-ppm signal intensity decreases while the signal intensity at 30.5 ppm simultaneously increases. The 30.5 ppm signal is assigned to an inner methylene group with a trans-gauche conformation. Subsequently, upon cooling, the signal at 33 ppm recovers, even after C(n)LSiloxanes have melted. In situ X-ray diffraction measurements at controlled temperatures reveal that the ordered arrangement of the long alkyl chains becomes disordered with elevating temperatures and reordered upon cooling to RT. In situ high-resolution solid-state Si-29 NMR analysis shows that the melting-solidification process progresses without any structural change in siloxane sheets of the C(n)LSiloxanes. Thus, the in situ analyses show that disordering of the long alkyl chains causes the C(n)LSiloxanes to melt. Because the majority of long alkyl chains are packed again in the ordered arrangement with the all-trans conformation upon cooling, the C(n)LSiloxanes are reversibly solidified and the C(n)LSiloxane structure is recovered.
  • Peijie Yang, The late Junxiang He, Akihiko Yamagishi, Hisako Sato
    Clay Science 20 (2) 27 - 30 0009-8574 2016/06 [Peer-reviewed]
  • Sumio Kaizaki, Dai Shirotani, Keiko Toya, Masako Iwamatsu, Yumiko Kato, Mikiko Maki, Takanori Hirami, Hiroshi Seki, Hiroyasu Nakata, Hisako Sato
    JOURNAL OF CERAMIC PROCESSING RESEARCH 17 (5) 464 - 467 1229-9162 2016/05 [Peer-reviewed]
     Scientific journal 
    This paper concerns with the synthesis and the luminescence spectra of lanthanide complexes of EuIII) and/or Eu(II) or Tb(III) ions which are embedded into fibrous palygorskite and sepiolite clays in which the magnesium ion are ion exchanged with lanthanide ions. The He-Cd laser excitation photoluminescence of the present complexes without organic ligands exhibit the deferration effects. The phosphors with light harvesting ligands such as benzophenone derivatives and 1,10-phenanthroline give the fairly strong visible luminescence by UV-A light excitation with a LED black light in a light room under fluorescent lamps. Further, the temperature dependent phosphors with benzophenone derivatives exhibit the stronger luminescence with increasing the temperature over 100 degrees C.
  • Hisako Sato, Tomoko Yajima, Akihiko Yamagishi
    CHIRALITY 28 (5) 361 - 364 0899-0042 2016/05 [Peer-reviewed]
     Scientific journal 
    Vibrational circular dichroism (VCD) spectroscopy was applied to gelation by a chiral low-molecular mass weight gelator, N,N'-diperfluoroalkanoyl-1,2-trans-diaminocyclohexane. Attention was focused on the winding effects of (-CF2)(n) chains on the gelating ability. For this purpose, a series of gelators were synthesized with perfluoroalkyl chains of different length (n = 6-8). When gelation was studied using acetonitrile as a solvent, the fibrils took different morphologies, depending on the chain length: twisted saddle-like ribbon or helical ribbon from fibril (n = 6) and a helical ribbon from platelet (n = 8). The signs of VCD peaks assigned to the couplet of C=O stretching and to the C-F stretching were also dependent on n, indicating that a gelator molecule changed conformation on elongating perfluoroalkyl chains. A model is proposed for the aggregation modes in fibrils. (C) 2016 Wiley Periodicals, Inc.
  • Kazuhiro Shikinaka, Hiroto Kikuchi, Tei Maki, Kiyotaka Shigehara, Hiroyasu Masunaga, Hisako Sato
    LANGMUIR 32 (15) 3665 - 3669 0743-7463 2016/04 [Peer-reviewed]
     Scientific journal 
    Macroscopic continuous hierarchical ordering of achiral nanotube "imogolite" was achieved by thixotropic gelation of imogolite with chiral hydroxy acid and their flow-orienting/subsequent standing for uniaxial alignments of imogolite. The chirality change of the hydroxy acids resulted in an inversion of the helical ordering. The study presented here first exhibits the millimeter-scale supramolecular chirality induced by angstrom scale molecular handedness in the architecture of nanotubes.
  • SATO Hisako, KANEKO Yoshiro, MORITA Masatoshi, TAMURA Kenji, YAMAGISHI Akihiko
    Clay Science 20 (1) 7‐11  0009-8574 2016/03 [Peer-reviewed]
  • KOMATSU Masataka, TAMURA Kenji, SARUWATARI Kazuko, YAMAGISHI Akihiko, SATO Hisako
    Clay Science 20 (1) 13‐19  0009-8574 2016/03 [Peer-reviewed]
  • Toshiyuki Sasaki, Yoko Ida, Ichiro Hisaki, Seiji Tsuzuki, Norimitsu Tohnai, Gerard Coquerel, Hisako Sato, Mikiji Miyata
    CRYSTAL GROWTH & DESIGN 16 (3) 1626 - 1635 1528-7483 2016/03 [Peer-reviewed]
     Scientific journal 
    Crystals belonging to PI and P2(1) space groups are fascinating research targets because of their potential applications in various fields by taking advantage of their chirality and polarity. However, molecules intrinsically prefer symmetric, achiral nonpolar space groups due to canceling out of dipole moments and close packing in crystalline states. Therefore, it remains difficult to selectively obtain the P1 and P2(1) crystals, especially from achiral molecules. Here we achieve construction of the chiral P1 and P2(1) crystals from achiral molecules based on stacking control of chiral two-dimensional hydrogen-bonded layers by halogen bonds (XBs). Precise investigations and theoretical calculations of their crystal structures revealed that space group selectivity among the chiral P1, P2(1), and achiral space groups is the result of a subtle balance between the stronger interaction: charge-assisted hydrogen bonds and the weaker interactions: van der Waals interaction of alkyl chains and the bonding involving halogens, which have anisotropic nature and robustness-tunability. It is also noteworthy that type II XBs were observed in chiral crystals, while type I halogen center dot center dot center dot halogen contacts were formed in achiral crystals, indicating the importance of type II XBs for chiral crystallization.
  • 赤外放射光の円偏光特性を利用した振動円二色性測定
    池本夕佳, 佐藤久子, 森脇太郎
    SPring-8利用研究成果集 185 - 189 2016 [Peer-reviewed]
  • Akihiko Yamagishi, Takeshi Kawasaki, Kei Hiruma, Hisako Sato, Takafumi Kitazawa
    DALTON TRANSACTIONS 45 (18) 7823 - 7828 1477-9226 2016 [Peer-reviewed]
     Scientific journal 
    A series of bimetallic coordination polymers with the elemental composition of [(CdL2)-L-II][Au(CN)(2)](2), (L = 3-methylpyridine, 4-ethylpyridine, 3,5-lutidine and 3-fluoropyridine) were synthesized and their crystal structures were determined. In all of the investigated compounds, there existed a pair of Au-Au atoms whose interatomic distance was shorter than the sum of van der Waals radii (0.36 nm) as an indication of the aurophilic interaction. The compounds were emissive under the irradiation at 370 nm. The emission spectra recorded in the temperature range of 183-363 K were characterized by the vibronic structures with a peak spacing (Delta nu) of ca. 2000 cm(-1). The value of Delta nu was close to the stretching vibration of the coordinated C N (2150-2170 cm(-1)). It was postulated that C N groups participated in the emission processes through their vibronic coupling. In the case of L = 4-ethylpyridine, the lifetime of emission was measured in the same temperature range, leading to the conclusion that the activation energy of the non-radiative processes (Delta E-a) was estimated to be 20 kJ mol(-1).
  • Hisako Sato, Tomoko Yajima, Akihiko Yamagishi
    CHIRALITY 27 (10) 659 - 666 0899-0042 2015/10 [Peer-reviewed]
     
    The attempts of applying chiroptical spectroscopy to supramolecular chirality are reviewed with a focus on vibrational circular dichroism (VCD). Examples were taken from gels, solids, and monolayers formed by low-molecular mass weight chiral gelators. Particular attention was paid to a group of gelators with perfluoroalkyl chains. The effects of the helical conformation of the perfluoroalkyl chains on the formation of chiral architectures are reported. It is described how the conformation of a chiral gelator was determined by comparing the experimental and theoretical VCD spectra together with a model proposed for the molecular aggregation in fibrils. The results demonstrate the potential utility of the chiroptical method in analyzing organized chiral aggregates. Chirality 27:659-666, 2015. (c) 2015 Wiley Periodicals, Inc.
  • Kenji Tamura, Hisako Sato, Akihiko Yamagishi
    JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY 303 (3) 2205 - 2210 0236-5731 2015/03 [Peer-reviewed]
     Scientific journal 
    Cs+ ions intercalated in a South African vermiculite were so firmly bound that they were hardly dissociated on treating with an aqueous solution of 1 M KNO3 or NH4NO3. When a vermiculite having adsorbed the saturated amount of Cs+ ions (0.61 mol g(-1)) was stirred in an aqueous solution containing 0.4 M of Mg(NO3)(2) and 20 mM of tetra kis(4-fluorophenyl)borate sodium salt (denoted as Na+L-), the intercalated Cs+ ions were fully replaced with Mg2+ ions within 2 h. The results were rationalized in terms of the ion-exchange reaction between Cs+ and Mg2+ ions: , in which the reverse reaction (or re-binding) of Cs+ ions was prohibited by the formation of an insoluble salt, Cs+L-.
  • Photoluminescence properties of hybrid Langmuir-Blodgett films of amphiphilic iridium complexes with the exfoliated nanosheets on Al coated glass substrate
    Ryotaro Ozaki, Mitsuki Yoneda, Shohei Masaki, Kazunori Kadowaki, Hisako Sato
    Eighth International conference on Molecular Electronics and Bioelectronics C-P02  2015
  • Kenji Tamura, Jun Yoshida, Masahiro Taniguchi, Takafumi Kitazawa, Akihiko Yamagishi, Hisako Sato
    DALTON TRANSACTIONS 44 (7) 3209 - 3215 1477-9226 2015 [Peer-reviewed]
     Scientific journal 
    Dinuclear square planar palladium(II) complexes, [{Pd(II) L-a}(2)(baet)] (La- = beta-diketonato and baet(2-) = 1,2-diacetyl- 1,2-bis(3-methylbutanoyl)ethanato), were prepared and used as chiral dopants to induce chiral nematic phases. The following beta-diketones were used as L-a-H: pentane-2,4-dione (acacH), dibenzoyl-methane (dbmH), di-4-nonyloxybenzoylmethane (C-9-dbmH) and 3-[4'-(4 ''-(octyloxy)phenylazo)phenyl]2,4- dione (C-8-azoacacH). When the enantiomers were doped in a nematic liquid crystal, they induced a chiral nematic phase with a helical twisting power (HTP) of 5-50 mu m(-1). In particular, the sample doped with [{Pd(II)(C-8-azoacac)}(2)(baet)] exhibited a reversible change of the circular dichroism spectrum under alternate irradiation at 350 nm and 460 nm. It implied that the HTP changed reversibly in response to the cis-trans isomerization of the coordinated C-8-azoacac ligand.
  • Kenji Tamura, Akihiko Yamagishi, Takafumi Kitazawa, Hisako Sato
    PHYSICAL CHEMISTRY CHEMICAL PHYSICS 17 (28) 18288 - 18293 1463-9076 2015 [Peer-reviewed]
     Scientific journal 
    Energy transfer was investigated between two types of iridium(III) complexes, [Ir(dfppy)(2)(C-n-bpy)](+) (dfppyH = 2-(2',4'-difluorophenyl)pyridine; C-n-bpy = 4,4'-dialkyl-2,2'-bipyridine dialkyl = dimethyl (C-1), didodecyl (C-12), and dinonyldecyl (C-19)) and [Ir(piq)(2)(C-n-bpy)](+) (piqH = 1-phenylisoquinoline) as a donor and an acceptor, respectively. The complexes were co-adsorbed by colloidally dispersed synthetic saponite. The efficiency of energy transfer (eta ET) was obtained from emission spectra at various donor-to-acceptor ratios (D/A) on the basis of the Forster-type energy transfer mechanism. For C-1-bpy, eta ET was as high as 0.5 with a D/A of ca. 20. The results implied that the photon energy captured by several donor molecules was collected by a single acceptor molecule (i.e. the harvesting of light energy). Enantioselectivity was observed, which indicates the participation of a contact pair of donor and acceptor molecules. For C-12-bpy and C-19-bpy, eta ET was low and exhibited no enantioselectivity, because their long alkyl chains inhibited close contact between the donor and acceptor molecules.
  • Kenji Tamura, Jun Yoshida, Masahiro Taniguchi, Takafumi Kitazawa, Akihiko Yamagishi, Hisako Sato
    DALTON TRANSACTIONS 44 (7) 3209 - 3215 1477-9226 2015 [Peer-reviewed]
     Scientific journal 
    Dinuclear square planar palladium(II) complexes, [{Pd(II) L-a}(2)(baet)] (La- = beta-diketonato and baet(2-) = 1,2-diacetyl- 1,2-bis(3-methylbutanoyl)ethanato), were prepared and used as chiral dopants to induce chiral nematic phases. The following beta-diketones were used as L-a-H: pentane-2,4-dione (acacH), dibenzoyl-methane (dbmH), di-4-nonyloxybenzoylmethane (C-9-dbmH) and 3-[4'-(4 ''-(octyloxy)phenylazo)phenyl]2,4- dione (C-8-azoacacH). When the enantiomers were doped in a nematic liquid crystal, they induced a chiral nematic phase with a helical twisting power (HTP) of 5-50 mu m(-1). In particular, the sample doped with [{Pd(II)(C-8-azoacac)}(2)(baet)] exhibited a reversible change of the circular dichroism spectrum under alternate irradiation at 350 nm and 460 nm. It implied that the HTP changed reversibly in response to the cis-trans isomerization of the coordinated C-8-azoacac ligand.
  • Kenji Tamura, Akihiko Yamagishi, Takafumi Kitazawa, Hisako Sato
    PHYSICAL CHEMISTRY CHEMICAL PHYSICS 17 (28) 18288 - 18293 1463-9076 2015 [Peer-reviewed]
     Scientific journal 
    Energy transfer was investigated between two types of iridium(III) complexes, [Ir(dfppy)(2)(C-n-bpy)](+) (dfppyH = 2-(2',4'-difluorophenyl)pyridine; C-n-bpy = 4,4'-dialkyl-2,2'-bipyridine dialkyl = dimethyl (C-1), didodecyl (C-12), and dinonyldecyl (C-19)) and [Ir(piq)(2)(C-n-bpy)](+) (piqH = 1-phenylisoquinoline) as a donor and an acceptor, respectively. The complexes were co-adsorbed by colloidally dispersed synthetic saponite. The efficiency of energy transfer (eta ET) was obtained from emission spectra at various donor-to-acceptor ratios (D/A) on the basis of the Forster-type energy transfer mechanism. For C-1-bpy, eta ET was as high as 0.5 with a D/A of ca. 20. The results implied that the photon energy captured by several donor molecules was collected by a single acceptor molecule (i.e. the harvesting of light energy). Enantioselectivity was observed, which indicates the participation of a contact pair of donor and acceptor molecules. For C-12-bpy and C-19-bpy, eta ET was low and exhibited no enantioselectivity, because their long alkyl chains inhibited close contact between the donor and acceptor molecules.
  • Tomoko Yajima, Erika Tabuchi, Emiko Nogami, Akihiko Yamagishi, Hisako Sato
    RSC ADVANCES 5 (98) 80542 - 80547 2046-2069 2015 [Peer-reviewed]
     Scientific journal 
    With a purpose of solidifying fluorous solvents, a novel series of perfluorinated gelators based on 1,2-diaminocyclohexane (denoted as CFn: n = the number of carbon chain in perfluoroalkanoyl moiety) were developed. The gelation ability for C6F6 was investigated. The length of a perfluoroalkyl chain (n = 4-9) was found to affect critically the gelation properties such as gel stability, chirality effects and aggregation modes in fibrils.
  • Hisako Sato, Miwa Ochi, Masaru Kato, Kenji Tamura, Akihiko Yamagishi
    NEW JOURNAL OF CHEMISTRY 38 (12) 5715 - 5720 1144-0546 2014/12 [Peer-reviewed]
     Scientific journal 
    Multi-layered hybrid films comprised of amphiphilic cationic iridium(III) complexes and the exfoliated layers of synthetic saponite were prepared by the modified Langmuir-Blodgett method. Two iridium(III) complexes, [Ir(dfppy)(2)(dc9bpy)](+) (dfppyH = 2-(4',6'-difluorophenyl)pyridine; dc9bpy = 4,4'-dinonyl-2,2'-bipyridine) and [Ir(dfppy)(2)(dc9bpy)(+) (piqH = 1-phenyisoquinoline), were used as blue (donor) and red emitters (acceptor), respectively. A non-luminescent hybrid layer of stearylammonium and synthetic saponite was deposited in a layer-by-layer manner to vary the distance between the donor and acceptor layers. Energy transfer was analysed according to the Forster-type mechanism with a focus on the dependence of its efficiency on the interlayer distance.
  • Hisako Sato, Miwa Ochi, Masaru Kato, Kenji Tamura, Akihiko Yamagishi
    NEW JOURNAL OF CHEMISTRY 38 (12) 5715 - 5720 1144-0546 2014/12 Scientific journal 
    Multi-layered hybrid films comprised of amphiphilic cationic iridium(III) complexes and the exfoliated layers of synthetic saponite were prepared by the modified Langmuir-Blodgett method. Two iridium(III) complexes, [Ir(dfppy)(2)(dc9bpy)](+) (dfppyH = 2-(4',6'-difluorophenyl)pyridine; dc9bpy = 4,4'-dinonyl-2,2'-bipyridine) and [Ir(dfppy)(2)(dc9bpy)(+) (piqH = 1-phenyisoquinoline), were used as blue (donor) and red emitters (acceptor), respectively. A non-luminescent hybrid layer of stearylammonium and synthetic saponite was deposited in a layer-by-layer manner to vary the distance between the donor and acceptor layers. Energy transfer was analysed according to the Forster-type mechanism with a focus on the dependence of its efficiency on the interlayer distance.
  • Hisako Sato, Miwa Ochi, Masaru Kato, Kenji Tamura, Akihiko Yamagishi
    NEW JOURNAL OF CHEMISTRY 38 (12) 5715 - 5720 1144-0546 2014/12 [Peer-reviewed]
     Scientific journal 
    Multi-layered hybrid films comprised of amphiphilic cationic iridium(III) complexes and the exfoliated layers of synthetic saponite were prepared by the modified Langmuir-Blodgett method. Two iridium(III) complexes, [Ir(dfppy)(2)(dc9bpy)](+) (dfppyH = 2-(4',6'-difluorophenyl)pyridine; dc9bpy = 4,4'-dinonyl-2,2'-bipyridine) and [Ir(dfppy)(2)(dc9bpy)(+) (piqH = 1-phenyisoquinoline), were used as blue (donor) and red emitters (acceptor), respectively. A non-luminescent hybrid layer of stearylammonium and synthetic saponite was deposited in a layer-by-layer manner to vary the distance between the donor and acceptor layers. Energy transfer was analysed according to the Forster-type mechanism with a focus on the dependence of its efficiency on the interlayer distance.
  • Hisako Sato, Kenji Tamura, Masahiro Taniguchi, Akihiko Yamagishi
    APPLIED CLAY SCIENCE 97-98 84 - 90 0169-1317 2014/08 [Peer-reviewed]
     Scientific journal 
    In order to investigate energy transfer on a clay surface, blue- and red- emitting cationic iridium(III) complexes, [Ir(dfppy)(2)L](+) (dfppyH = 2-(4',6'-difluorophenyl)pyridine, L = 4,4'-dimethy1-2,2'-bipyridine) and [Ir(piq)(2)L](+) (piqH = 1-phenyisoquinoline), respectively, were co-adsorbed by colloidally dispersed synthetic saponite in 1:3 (v/v) methanol/water. The stationary and transient emission results were analyzed on the basis of the Forstertype energy transfer mechanism. It was concluded that energy transfer took place from the excited blue emitter to the red one efficiently. The accumulation of the reactants on a clay particle was essential, since no energy transfer occurred in the absence of a clay in the similar concentration ranges. (c) 2014 Elsevier B.V. All rights reserved.
  • Hisako Sato, Kenji Tamura, Akihiko Yamagishi
    Chemosensors 2 41 - 55 2014/03 
    © 2014 by the authors. The use of Ir(III) complexes in photo-responsive molecular devices for oxygen gas sensing is reviewed. Attention is focused on the immobilization of Ir(III) complexes in organic or inorganic host materials such as polymers, silica and clays in order to enhance robustness and reliability. Our recent works on constructing nanometer-thick films comprised of cyclometalated cationic Ir(III) complexes and clay minerals are described. The achievement of multi-emitting properties in response to oxygen pressure is demonstrated.
  • Hisako Sato, Emiko Nogami, Tomoko Yajima, Akihiko Yamagishi
    RSC ADVANCES 4 (4) 1659 - 1665 2046-2069 2014 [Peer-reviewed]
     Scientific journal 
    Gel formation by low molecular mass gelators was investigated. The gelator was trans(RR)- or trans(SS)-N, N'-n-bromoalkanoyl-1,2-diaminocyclohexane (denoted as RR-CnBr or SS-CnBr, respectively; n = the number of carbon atoms in an alkanoyl group). When n was varied from 5 to 12, the gelators formed transparent or opaque or turbid gels in benzene except for n = 8. Focusing on the end effects, the gelation behavior of CnBr was compared with that of non-brominated counterparts (denoted as RR- or SS-Cn). From the vibrational circular dichroism (VCD) spectra of enantiomeric gelator/benzene-d(6) gels, the signs of the coupled peaks around 1640 cm(-1), which were assigned to the symmetric and asymmetric C=O stretching vibrations from the higher to lower wavenumber, respectively, were opposite between SS-CnBr and SS-Cn (or between RR-CnBr and RR-Cn). On the other hand, the signs of the coupled peaks around 1550 cm(-1) assigned to the NH stretching vibrations remained unaffected. The observed reversal of the signs in the C=O couplet was rationalized in terms of the different modes of stacking in fibrils. In the case of Cn, for example, the molecules were stacked through anti-parallel double intermolecular hydrogen bonds using two pairs of >NH and >C=O groups, while, in the case of CnBr, a single intermolecular hydrogen bond was formed with the remaining pair of >NH and >C=O groups forming an intramolecular hydrogen bond. Single crystal X-ray analyses were performed for SS-C6Br and SS-C8Br. The results demonstrated that the length of the bromoalkanoyl chains drastically affected the packing modes in crystalline states.
  • Hisako Sato, Kenji Tamura, Keishi Ohara, Shin-ichi Nagaoka
    NEW JOURNAL OF CHEMISTRY 38 (1) 132 - 139 1144-0546 2014/01 [Peer-reviewed]
     Scientific journal 
    Mono- and multi-layered films comprised of amphiphilic cationic iridium(III) complexes hybridized with the exfoliated nanosheets of synthetic saponite were prepared by the modified Langmuir-Blodgett method. Three iridium(III) complexes with different emission maxima (lambda(max)) were used as incorporated complexes: [Ir(dfppy)(2)(dc9bpy)](+) (lambda(max) = 500 nm) (dfppyH = 2-(4',6'-difluorophenyOpyridine; dc9bpy = 4,4'-dinonY1-2,2'-bipyridine) [Ir(ppy)(2)(dc9bpy)](+) (lambda(max) = 550 nm) (ppyH = 2-phenylpyridine) and [Ir(piq)(2)(dc9bpy)](+) (lambda(max) = 590 nm) (piqH = 1-phenylisoquinoline) for blue, yellow and red emissions, respectively. Six triple-layered films with different layer sequences were fabricated by layer-by-layer deposition onto quartz substrates. Stationary emission spectra were recorded on the prepared films under vacuum and at various oxygen pressures Notably the change in the spectral shape at surrounding oxygen pressure depended remarkably on the layer sequence. Quenching by oxygen molecules was analyzed by applying a two-site model to the Stern-Volmer plots. The present nanometer-thick films were regarded as a benchmark for an optical device emitting different visible lights in response to oxygen pressure.
  • Hisako Sato, Tomoko Yajima, Akihiko Yamagishi
    RSC ADVANCES 4 (49) 25867 - 25870 2046-2069 2014 [Peer-reviewed]
     Scientific journal 
    A 4 : 1 (v/v) mixture of CD3CN and C6F6 was gelated by a chiral low-molecular weight gelator, N,N'-diperfluoroheptanoyl-1,2(R, R)- or -1,2(S, S)-diaminocyclohexanel. The process from a viscous isotropic solution to a stable gel was monitored by vibrational circular dichroism (VCD) spectroscopy. The transient VCD spectra revealed that an intermediate state existed, which was characterized by the less stable conformation of a gelator molecule.
  • Toshiyuki Sasaki, Ichiro Hisaki, Tetsuya Miyano, Norimitsu Tohnai, Kazuya Morimoto, Hisako Sato, Seiji Tsuzuki, Mikiji Miyata
    NATURE COMMUNICATIONS 4 2041-1723 2013/04 [Peer-reviewed]
     Scientific journal 
    Chiral molecules preferentially form one-handed supramolecular assemblies that reflect the absolute configuration of the molecules. Under specific conditions, however, the oppositehanded supramolecular assemblies are also obtained because of flexibility in the bond length and reversibility of non-covalent interactions. The mechanism of the handedness selectivity or switching phenomenon remains ambiguous, and most phenomena are observed by chance. Here we demonstrate the construction of chiral hydrogen-bonded twofold helical assemblies with controlled handedness in the crystalline state based on crystallographic studies. Detailed investigation of the obtained crystal structures enabled us to clarify the mechanism, and the handedness of the supramolecular chirality was successfully controlled by exploiting achiral factors. This study clearly reveals a connection between molecular chirality and supramolecular chirality in the crystalline state.
  • Hisako Sato, Yukie Mori, Takafumi Kitazawa, Akihiko Yamagishi
    DALTON TRANSACTIONS 42 (1) 232 - 237 1477-9226 2013 [Peer-reviewed]
     Scientific journal 
    Mononuclear and dinuclear ruthenium(III) complexes with bis-beta-diketonato ligands (denoted by [Ru(acac)(2)(L-LH)] and [Ru(acac)(2)(L-L)Ru(acac)(2)], respectively) were synthesized, where acac, L-LH- and L-L2- denote acetylacetonato, monoprotonated and unprotonated bis-beta-diketonato ligands, respectively. The following three ligands were used as the bis-beta-diketonato ligand (L-L2-): 1,2-diacetyl-1,2-dibenzoyl-ethanato (denoted by dabe(2-)), 1,2-diacetyl-1,2-bis(3-methylbutanoyl)ethanato (baet(2-)) and 1,2-diacetyl-1,2- dipropanoylethanato (dpe(2-)). For the mononuclear and the meso-type dinuclear complexes, a pair of diastereomeric species were identified as Delta-(or Delta-) [Ru(acac)(2)(R- orS-L-LH)] and [Delta-Ru(acac)(2)(R- or S-L-L)Delta-Ru(acac)(2)], respectively. The possibility of thermal inversion in coordinated L-LH- (mononuclear) or L-L2-(dinuclear) was pursued by monitoring the changes in the electronic circular dichroism or the H-1 NMR spectra. No inversion occurred for the dinuclear complexes, when their chloroform solutions were kept at 50 degrees C for ca. 100 h. In contrast, some of the mononuclear complexes underwent the inversion of axial chirality to give an equilibrium mixture under the same conditions. The reaction followed the first-order rate law and the overall first-order rate constants (k) of [Ru(acac) 2(L-LH)] were determined to be k = 0.13, 0.0048 and less than 0.001 h(-1) for L-LH- = dabeH(-), baetH(-) and dpeH(-), respectively. The results suggest that the main factor determining the barrier height of the internal rotation is not the steric but the electronic properties of the carbon-carbon bond connecting the two beta-diketonato moieties.
  • Hisako Sato, Yukie Mori, Takafumi Kitazawa, Akihiko Yamagishi
    DALTON TRANSACTIONS 42 (1) 232 - 237 1477-9226 2013 Scientific journal 
    Mononuclear and dinuclear ruthenium(III) complexes with bis-beta-diketonato ligands (denoted by [Ru(acac)(2)(L-LH)] and [Ru(acac)(2)(L-L)Ru(acac)(2)], respectively) were synthesized, where acac, L-LH- and L-L2- denote acetylacetonato, monoprotonated and unprotonated bis-beta-diketonato ligands, respectively. The following three ligands were used as the bis-beta-diketonato ligand (L-L2-): 1,2-diacetyl-1,2-dibenzoyl-ethanato (denoted by dabe(2-)), 1,2-diacetyl-1,2-bis(3-methylbutanoyl)ethanato (baet(2-)) and 1,2-diacetyl-1,2- dipropanoylethanato (dpe(2-)). For the mononuclear and the meso-type dinuclear complexes, a pair of diastereomeric species were identified as Delta-(or Delta-) [Ru(acac)(2)(R- orS-L-LH)] and [Delta-Ru(acac)(2)(R- or S-L-L)Delta-Ru(acac)(2)], respectively. The possibility of thermal inversion in coordinated L-LH- (mononuclear) or L-L2-(dinuclear) was pursued by monitoring the changes in the electronic circular dichroism or the H-1 NMR spectra. No inversion occurred for the dinuclear complexes, when their chloroform solutions were kept at 50 degrees C for ca. 100 h. In contrast, some of the mononuclear complexes underwent the inversion of axial chirality to give an equilibrium mixture under the same conditions. The reaction followed the first-order rate law and the overall first-order rate constants (k) of [Ru(acac) 2(L-LH)] were determined to be k = 0.13, 0.0048 and less than 0.001 h(-1) for L-LH- = dabeH(-), baetH(-) and dpeH(-), respectively. The results suggest that the main factor determining the barrier height of the internal rotation is not the steric but the electronic properties of the carbon-carbon bond connecting the two beta-diketonato moieties.
  • Hisako Sato, Akihiko Yamagishi
    International Journal of Molecular Sciences 14 (1) 964 - 978 1661-6596 2013/01 [Peer-reviewed]
     
    The present article reviews the results on the application of vibrational circular dichroism (VCD) spectroscopy to the study of stereochemical properties of chiral metal complexes in solution. The chiral characters reflecting on the vibrational properties of metal complexes are revealed by measurements of a series of β-diketonato complexes with the help of theoretical calculation. Attention is paid to the effects of electronic properties of a central metal ion on vibrational energy levels or low-lying electronic states. The investigation is further extended to the oligomers of β-diketonato complex units. The induction of chiral structures is confirmed by the VCD spectra when chiral inert moieties are connected with labile metal ions. These results have demonstrated how VCD spectroscopy is efficient in revealing the static and dynamic properties of mononuclear and multinuclear chiral metal complexes, which are difficult to clarify by means of other spectroscopes. © 2013 by the authors licensee MDPI, Basel, Switzerland.
  • Kazuko Fujii, Hiroshi Kodama, Nobuo Iyi, Taketoshi Fujita, Kenji Kitamura, Hisako Sato, Akihiko Yamagishi, Shigenobu Hayashi
    NEW JOURNAL OF CHEMISTRY 37 (4) 1142 - 1149 1144-0546 2013 [Peer-reviewed]
     Scientific journal 
    Meltable layered alkylsiloxanes (C(n)LSiloxanes) were synthesized from tetraethoxysilane and alkyltrialkoxysilanes with carbon numbers (n) of 12, 16, and 18 via hydrolysis and polycondensation at 100 and 150 degrees C under basic conditions. Differential scanning calorimetric (DSC) measurements revealed that C(n)LSiloxanes melted reversibly at -0.8 to 51.3 degrees C, the melting points being dependent on n. Scanning electron microscope (SEM) images showed that thin plates were stacked. X-ray diffraction (XRD) peaks were observed at angles corresponding to distances (d) of 2.1, 2.5, and 2.8 nm for C-12-, C-16-, and C(18)LSiloxanes, respectively. High-resolution solid-state C-13 nuclear magnetic resonance (NMR) measurements showed that the organic moieties were alkylsilyl groups with long alkyl chains and that an all-trans conformation was dominant. This was supported by the XRD peak corresponding to a d value of 0.41 nm. High-resolution solid-state Si-29 NMR measurements demonstrated the presence of SiO4 and CSiO3 units. A structural model has been proposed for C(n)LSiloxanes, where siloxane sheets consisting of the SiO4 and CSiO3 units are stacked with the ordered interdigitated monolayer of the alkyl chains in between and are bonded covalently with the alkyl chains.
  • Hisako Sato, Yukie Mori, Akihiko Yamagishi
    DALTON TRANSACTIONS 42 (19) 6873 - 6878 1477-9226 2013 [Peer-reviewed]
     Scientific journal 
    Vibrational circular dichroism (VCD) spectroscopy was applied to study the structural change of a Ni(II) complex (denoted by [Ni(II)L]) with a chiral Schiff base ligand, (R)- or (S)-2,2'-bis(salicylideneamino)-1,1'-binaphthyl (denoted by H2L), in solution. The major signals in the mid-IR region were assigned on the basis of comparison with the DFT-calculated spectra. The complex transformed reversibly between the square-planar, tetrahedral and octahedral configurations, depending on solvents and temperature. The observed changes in the VCD peaks accompanying the transformation were analyzed in terms of the conformational change of the chiral ligand with a focus on the twisting angle in the Schiff base backbone and the dihedral angle of the binaphthyl group.
  • Hisako Sato, Fumi Sato, Akihiko Yamagishi
    CHEMICAL COMMUNICATIONS 49 (42) 4773 - 4775 1359-7345 2013 [Peer-reviewed]
     Scientific journal 
    We describe herein a concept of optical memory using a photosensitive metal complex, [Cr((-)-tfac)(3)] ((-)-tfac = (-)-3-trifluoroacetylcamphorato), as a dopant to induce chiral nematic phases. The memory was written by the photo-epimerization of the complex and read-out in terms of circular dichroism spectra. The rewritability of the memory was attempted by using the cycles between liquid crystals and isotropic phases.
  • Hisako Sato, Kazuya Morimoto, Yukie Mori, Yuji Shinagawa, Takafumi Kitazawa, Akihiko Yamagishi
    DALTON TRANSACTIONS 42 (21) 7579 - 7585 1477-9226 2013 [Peer-reviewed]
     Scientific journal 
    Mononuclear and dinuclear square planar palladium(II) complexes (denoted by [(hfac)Pd(II)(L-LH)] and [(hfac)Pd(II)(L-L)Pd(II)(hfac)], respectively) were synthesized. Here hfac(-), HL-L- and L-L2- denote hexafluoroacetylacetonato, monoprotonated and non-protonated bis-beta-diketonato ligands, respectively. Three bis-beta-diketones were used as HL-LH: 1,2-diacetyl-1,2-dibenzoylethane (denoted by dabeH(2)), 1,2-diacetyl-1,2-bis(3-methylbutanoyl)ethane (baetH(2)) and 1,2-diacetyl-1,2-propanoylethane (dpeH(2)). Both the monomeric and dimeric Pd(II) complexes were chiral due to the orthogonal twisting of the two non-symmetric diketonato moieties in HL-L- and L-L2-, respectively. Optical resolution of [(hfac)Pd(II)(dabe)Pd(II)(hfac)] was achieved chromatographically on a chiral column to obtain a pair of optical antipodes which were stable against racemization. As for the other complexes, resolution was possible only after replacing hfac(-) with a bulky ligand such as dibenzoylmethanato (dbm(-)). Although a dinuclear complex with a symmetric bis-beta-diketonato ligand, [(hfac)Pd(II)(taet)Pd(II)(hfac)] (taet(2-) = 1,1,2,2-tetraacetylethanato), was achiral, the replacement of the terminal ligands with non-symmetric beta-diketonates yielded an axially chiral complex such as [(phacac)Pd(II)(taet)Pd(II)(phacac)], wherein phacac(-) denotes 1-phenyl-1,3-butanedionato. The UV and CD spectra of the Pd(II) complexes were analyzed with the help of the TDDFT calculations. The chiral monomeric species, [(dbm)Pd(II)(R- or S-baetH)], formed a heterometallic tetranuclear complex, [Fe(III){(dbm)Pd(II)(R- or S-baet)}(3)], in methanol solution.
  • Sumio Kaizaki, Dai Shirotani, Hisako Sato
    PHYSICAL CHEMISTRY CHEMICAL PHYSICS 15 (24) 9513 - 9515 1463-9076 2013 [Peer-reviewed]
     Scientific journal 
    For Delta-SAPR-8-Cs[Ln((+)-hfbc)(4)]((+)-hfbc = (+)-heptafluoro-butyryl-camphorate; Cs-Ln), the vibrational circular dichroism pattern and intensity of Cs-La, Cs-Nd, Cs-Gd, Cs-Ho, Cs-Er, Cs-Lu and Cs-Sm, Cs-Eu, Cs-Tb, Cs-Dy, Cs-Tm, Cs-Yb, respectively, are correlated with the even and the odd parity of total orbital angular momentum in the ground state terms.
  • Takafumi Kitazawa, Kei Hiruma, Hisako Sato, Kenji Tamura, Akihiko Yamagishi
    DALTON TRANSACTIONS 42 (48) 16680 - 16682 1477-9226 2013 [Peer-reviewed]
     Scientific journal 
    A newly synthesized Hofmann-type bimetallic coordination polymer, [Cd-II(3-methylpyridine)(2)][Au(CN)(2)](2), was luminescent with emission peaks at 400 nm, 440 nm, 490 nm and 550 nm (shoulder) under irradiation at 360 nm, whose multiple peak character in the emission spectrum was rationalized in terms of the vibrational structures in the interactions between the Au atoms in adjacent layers.
  • Kazuya Morimoto, Takahiro Nakae, Keishi Ohara, Kenji Tamura, Shin-ichi Nagaoka, Hisako Sato
    NEW JOURNAL OF CHEMISTRY 36 (12) 2467 - 2471 1144-0546 2012/12 [Peer-reviewed]
     Scientific journal 
    Langmuir-Blodgett (LB) films were prepared by hybridizing a floating monolayer of an amphiphilic cationic iridium(m) complex with clay particles in a subphase. Two kinds of iridium(III) complexes were used: [Ir(dfppy)(2)(dc9bpy)](+) (denoted by DFPPY: dfppyH = 2-(4',6'-difluoro-phenyl)pyridine; dc9bpy = 4,4'-dinonyl-2,2'-bipyridine) with the maximum emission wavelength (lambda(max)) at 500 nm and [Ir(ppy)(2)(dc9bpy)](+) (denoted by PPY: ppyH = 2-phenylpyridine) with lambda(max) at 550 nm. Stationary emission spectra were recorded on the following films under vacuum: {DFPPY or PPY/clay}(n) (n = 1-3), {DFPPY/clay/PPY/clay} and {PPY/clay/DFPPY/clay}. The intensity of emission from {PPY/clay}(n) or {DFPPY/clay}(n) increased nearly in proportion to the layer number (n). Both DFPPY and PPY emitted simultaneously from {DFPPY/clay/PPY/clay}, indicating the low contribution of energy transfer. Contrarily PPY emitted exclusively from {PPY/clay/DFPPY/clay} as a result of the efficient quenching of excited DFPPY in the lower layer by PPY in the upper layer. The introduction of oxygen gas resulted in the decrease of emission for all films. Notably {DFPPY/clay/PPY/clay} exhibited a dual emitting character under an oxygen atmosphere, that is, the broad emission maximum was observed around 530 nm at lower oxygen pressure (0 < P-O2 < 4 kPa), while the emission peak shifted to 550 nm at higher oxygen pressure (P-O2 > 4 kPa).
  • Kazuya Morimoto, Toshihiro Kogure, Kenji Tamura, Saki Tomofuji, Akihiko Yamagishi, Hisako Sato
    CHEMISTRY LETTERS 41 (12) 1715 - 1717 0366-7022 2012/12 [Peer-reviewed]
     Scientific journal 
    Cesium ions (Cs+) strongly adsorbed in vermiculite clay (Verm) were efficiently desorbed by reacting with magnesium ions (Mg2+). 70-90% removal of adsorbed Cs+ ions was achieved when Verm loaded with 0.1-100 mu mol g(-1) Cs+ (corresponding to 0.016-16% of the saturation amount) was mixed with 3.0 mol L-1 aqueous Mg(NO3)(2). X-ray analyses and powder X-ray diffraction measurements on solid samples confirmed that ion exchange occurred between Cs+ ions in the interlayer space and Mg2+ ions.
  • Dai Shirotani, Kazuaki Yamanari, Reiko Kuroda, Takunori Harada, Jamie L. Lunkley, Gilles Muller, Hisako Sato, Sumio Kaizaki
    CHIRALITY 24 (12) 1055 - 1062 0899-0042 2012/12 [Peer-reviewed]
     Scientific journal 
    The preparation of tetrakis((+)-hfbc) lanthanide(III) complexes with an encapsulated alkali metal and ammonium ions M[Ln((+)-hfbc)4] (hereafter abbreviated as M-Ln?:?(+)-hfbc, (+)-heptafluorobutyrylcamphorate; M, ammonium or benzyl ammonium ions as well as alkali metal ions) was reported and discussed. The electronic circular dichroism (CD) spectra in the intraligand p-p* transition of MLn were examined in view of the solvent effect. Here, the concentration, alkali metal, and ammonium ion dependences are compared with the solid CD, 5D0???7F0(Eu(III)) excitation spectra, circularly polarized luminescence, and vibrational circular dichroism. It has been revealed that the dodecahedral eight coordinate DD-8-M-Ln complexes in crystals are equilibrated between the diastereoselectively formed square antiprism eight coordinate SAPR-8-M-Ln and [Ln((+)-hfbc)3] in EtOH and CH3CN solutions or between the SAPR-8-M-Ln and DD-D2d(mmmm)-8-M-Ln complexes in CHCl3 solution. The observed CD couplets are found to reflect the exciton CD couplets which are useful to determine the four-bladed SAPR-(llll) absolute configuration around the lanthanide(III) ion. Chirality 24:10551062, 2012. (c) 2012 Wiley Periodicals, Inc.
  • Akihiko Yamagishi, Hisako Sato
    CLAYS AND CLAY MINERALS 60 (4) 411 - 419 0009-8604 2012/08 [Peer-reviewed]
     Scientific journal 
    Attempts at optical resolution and asymmetric syntheses using smectite clay minerals are described. Use of the method was prompted by the discovery that the saturated adsorption of a tris(chelated) metal complex, [Ru(1,10-phenanthroline)3](2+), by Na-montmorillonite depended heavily on the stereochemical properties. The pure enantiomer was adsorbed by cation exchange at negative surface sites of the clay mineral, while the racemic mixture was adsorbed to two times excess of the cation exchange capacity. The chelate takes a uniform orientation on a clay mineral surface due to the matching between the molecular symmetry and the two-dimensional network of a phyllosilicate layer. On a clay mineral surface covered with the enantiomeric chelates, a vacant space capable of chiral discrimination was generated. Based on this, an ion-exchange adduct of smectite and the chiral chelate was used as an adsorbent for separating racemic mixtures or selectively producing either one of the optical isomers.
  • Toshihiro Kogure, Kazuya Morimoto, Kenji Tamura, Hisako Sato, Akihiko Yamagishi
    CHEMISTRY LETTERS 41 (4) 380 - 382 0366-7022 2012/04 [Peer-reviewed]
     Scientific journal 
    X-ray diffraction and high-resolution transmission electron microscopy showed that cesium ions (Cs+'s) in a vermiculite clay formed a segregated monoionic layer in the interlayer spaces. Each ion was fixed simultaneously at the centers of hexagonal rings in the upper and lower silicate tetrahedral sheets. No Cs+ was eluted even when Cs+-vermiculite was kept at 80 degrees C for 48 h in the presence of a large excess of Al(NO3)(3) or [Co(NH3)(6)]Cl-3.
  • Takahiro Nakae, Ryuji Ohnishi, Yoshiharu Kitahata, Tatsuya Soukawa, Hisako Sato, Shigeki Mori, Tetsuo Okujima, Hidemitsu Uno, Hiroshi Sakaguchi
    TETRAHEDRON LETTERS 53 (13) 1617 - 1619 0040-4039 2012/03 [Peer-reviewed]
     Scientific journal 
    6,13-Diiododibenzo[a,h]anthracene and 5,8-diiodopicene were synthesized by AuCl-catalyzed double cyclization. The highly selective reaction yielded a new class of pen-halogenated fused aromatics. (C) 2012 Elsevier Ltd. All rights reserved.
  • Takahiro Nakae, Shingo Mizobuchi, Maki Yano, Takuya Ukai, Hisako Sato, Toru Shinmei, Toru Inoue, Tetsuo Irifune, Hiroshi Sakaguchi
    CHEMISTRY LETTERS 41 (2) 140 - 141 0366-7022 2012/02 [Peer-reviewed]
     Scientific journal 
    A two-step procedure of two-dimensional polymer constructed from benzo[b]trithiophene (BTT) was proposed by electrochemical polymerization and thermal conversion. Electropolymerized BTT oligomer on an electrode was thermally converted to conjugated polymer. Obtained conductive material is found to retain BTT structure by Raman spectra and to extend pi conjugation by absorption spectra.
  • Hisako Sato, Ryoichi Takase, Yukie Mori, Akihiko Yamagishi
    DALTON TRANSACTIONS 41 (3) 747 - 751 1477-9226 2012 [Peer-reviewed]
     Scientific journal 
    Dinuclear Ru(III) complexes, [Ru(III)(acac)(2)(dabe)Ru(III)(acac)(2)] (acacH = acetylacetone; dabeH(2) = 1, 2-diacetyl-1,2-dibenzoylethane) and [Ru(III)(acac)(2)(tbet)Ru(III)(acac)(2)] (tbetH(2) = 1,1,2,2-tetrabenzoylethane) were synthesized by reacting [Ru(acac)(2)(CH3CN)(2)]PF6 with dabeH(2) and tbetH(2) respectively, in toluene. The X-ray structural analysis of a meso-type dinuclear Ru(III) complex, Delta Lambda-[Ru(III)(acac)(2)(dabe)Ru(III)(acac)(2)], showed that the bridging part became chiral due to the orthogonal twisting of two non-symmetrical beta-diketonato moieties. To confirm this conclusion, the complex was resolved chromatographically to provide a pair of optical antipodes. Such chirality in the bridging part was not generated for [Ru(III)(acac)(2)(tbet)Ru(III)(acac)(2)], because the beta-diketonato moieties in tbet(2-) are symmetrical.
  • Hisako Sato, Fumi Sato, Masahiro Taniguchi, Akihiko Yamagishi
    DALTON TRANSACTIONS 41 (6) 1709 - 1712 1477-9226 2012 [Peer-reviewed]
     Scientific journal 
    Vibrational circular dichroism (VCD) spectroscopy was applied to study the stereochemical properties of a star-burst type tetranuclear Ru(III) complex, Delta-(or Lambda-)[{Delta-(or Lambda-)-Ru(III)(acac)(2)(taet)}(3)Ru(III)] (acac = acetylacetonato; taet = tetraacetylethanato). By comparing the VCD spectra of eight diastereomeric enantiomers, it was shown that the spectra reflected the homo- or hetero-chiral nature of the bridging part connecting the central core and the peripheral region.
  • Hisako Sato, Takahiro Nakae, Kazuya Morimoto, Kenji Tamura
    ORGANIC & BIOMOLECULAR CHEMISTRY 10 (8) 1581 - 1586 1477-0520 2012 [Peer-reviewed]
     Scientific journal 
    Vibrational circular dichroism (VCD) spectra were recorded on benzene-d(6) gels formed by chiral low molecular mass gelators (LMGs), trans(RR)- or trans(SS)-N,N'-alkanoyl-1,2-diaminocyclohexane (denoted by RR-C-n or SS-C-n, respectively; n = the number of carbon atoms in an introduced alkanoyl group). Attention was focused on the effects of alkyl chain length on the structures of the gels. When n was changed from 6 to 12, the signs of the coupled peaks around 1550 cm(-1) in the VCD spectra, which were assigned to the symmetric and asymmetric C=O stretching vibrations from the higher to lower wavenumber, respectively, critically depended on the alkyl chain length. In the case of RR-C-n, for example, the signs of the couplet were plus and minus for n = 8, 9, 10 and 12, while the signs of the same couplet were reversed for n = 6 and 7. The conformations of LMGs in fibrils were determined by comparing the observed IR and VCD spectra with those calculated for a monomeric molecule. The observed reversal of signs in the C=O couplet was rationalized in terms of the different modes of hydrogen bonding. In the case of C-8, C-9, C-10 and C-12, gelator molecules were stacked with their cyclohexyl rings in parallel, forming double anti-parallel chains of intermolecular hydrogen bonds using two pairs of >NH and >C=O groups. In case of C-6 and C-7, gelator molecules were stacked through a single chain of intermolecular hydrogen bonds using a pair of >NH and >C=O groups. The remaining pair of >NH and >C=O groups formed an intramolecular hydrogen bond.
  • Kazuhiro Kohno, Kazuya Morimoto, Naoko Manabe, Tomoko Yajima, Akihiko Yamagishi, Hisako Sato
    CHEMICAL COMMUNICATIONS 48 (32) 3860 - 3862 1359-7345 2012 [Peer-reviewed]
     Scientific journal 
    A chiral gelator, RR- or SS-N,N'-diperfluorooctanoyl-1,2-diaminocyclohexane, gelated racemic 2-butanol. The gel was most stable at the racemic mixture, its stability lowered with the increase in the optical purity of the gelator. Notably, characteristic helically coiled fibrils were formed in the narrow region of enantiomer excess (ee = 0.2-0.4). Promotion effects of the antipodal enantiomers are proposed.
  • Dai Shirotani, Hisako Sato, Kazuaki Yamanari, Sumio Kaizaki
    DALTON TRANSACTIONS 41 (35) 10557 - 10567 1477-9226 2012 [Peer-reviewed]
     Scientific journal 
    For electronic circular dichroism in the 4f-4f transitions (4f-4f CD) of a series of nine tetrakis ((+)-3-heptafluorobutyrylcamphorato) Ln(III) complexes,Delta-SAPR-8-C-4(llll) Cs[Ln((+)-hfbc)(4)]center dot H2O (Cs-Ln = Cs-Pr, -Nd, -Sm, -Eu, -Dy, -Ho, -Er, -Tm, -Yb), the spectroscopic observables such as the dissymmetry factor g = Delta epsilon/epsilon values with the intensities (Delta epsilon) of the CD components and the molar absorption intensities (epsilon) in the 4f-4f transitions between the L-2S+1(J) levels are compared with each other to test the classification of the CD components in the relative order of the observables predicted in terms of the selection rule for 4f-4f transitions. The 4f-4f CD-based chiroptical spectra-structural relationship across the series of Delta-SAPR-8-C-4(llll) lanthanide(III) complexes is proposed: the signs of the 4f-4f CD or CPL in the hypersensitive transitions are related to the absolute configuration; Ln complexes with a negative CD component have the Delta-configuration around Ln(III) and vice versa.
  • Hirotoshi Mori, Akihiko Yamagishi, Hisako Sato
    JOURNAL OF CHEMICAL PHYSICS 135 (8) 0021-9606 2011/08 [Peer-reviewed]
     Scientific journal 
    The open-shell density functional theory calculations with M06 exchange-correlation functional and all-electron Douglas-Kroll second order scalar relativistic correction were performed to interpret the vibrational circular dichroism (VCD) spectra of four kinds of tris(acetylacetonato) metal(III), [M(III)(acac)(3)] (acac = acetylacetonato, M = Ru, Cr, Co, and Rh). It was deduced that the experimental spectra were well reproduced by the calculation with harmonic approximation in case of [Co(III)(acac)(3)] (d(6); S = 0), [Rh(III)(acac)(3)] (d(6); S = 0), and [Ru(III)(acac)(3)] (d(5); S = 1/2). In case of [Cr(III)(acac)(3)] (d(3); S = 3/2), anharmonic effects should be taken into account to predict the accurate vibrational frequencies of closely located modes. Time-dependent density functional theory calculations were performed to estimate the contribution of excited states in the VCD spectra. As a consequence, the presence of the low-lying excited states was predicted for [Ru(III)(acac)(3)] alone, which agreed with the experimental observation. (C) 2011 American Institute of Physics. [doi:10.1063/1.3624605]
  • Kazuya Morimoto, Kenji Tamura, Yasushi Umemura, Hisako Sato, Akihiko Yamagishi
    CHEMISTRY LETTERS 40 (8) 867 - 869 0366-7022 2011/08 [Peer-reviewed]
     Scientific journal 
    The use of smectite-type clay minerals is proposed for capturing radioactive nuclear wastes from sea water. Iodine molecules dissolved in a 3 wt% aqueous NaCl solution were completely taken up by a column packed with Ag-modified synthetic saponite. Cs+ and Sr2+ ions in a 3 wt% aqueous NaCl solution were adsorbed efficiently on a column packed with magnesium vermiculite under appropriate conditions.
  • Hisako Sato, Kenji Tamura, Rie Aoki, Masako Kato, Akihiko Yamagishi
    CHEMISTRY LETTERS 40 (1) 63 - 65 0366-7022 2011/01 [Peer-reviewed]
     Scientific journal 
    Emission from a cationic cyclometalated iridium(III) complex, Delta- or Lambda-[Ir(ppy)(2)(dmbpy)](+) (Hppy: 2-phenylpyridine and dmbpy: 4,4'-dimethyl-2,2'-bipyridine), adsorbed on a colloidal saponite clay was quenched stereoselectively by chiral [Ru(acac)(3)] (acac: acetylacetonato) in a solution at the overall selectivity factor of K-SVo(Delta-Delta or Lambda-Lambda)/K-SVo(Delta-Lambda) = 1.84 in favor of the pseudo-enantiomeric pair between the emitter and the quencher.
  • Hisako Sato, Takara Sakurai, Akihiko Yamagishi
    CHEMISTRY LETTERS 40 (1) 25 - 27 0366-7022 2011/01 [Peer-reviewed]
     Scientific journal 
    Vibrational circular dichroism spectroscopy is applied to the gels and Langmuir-Blodgett (LB) films of R- and S-12-HOA deposited on glass substrates (50 X-type layers) in the wave-number region of 2700-3400 cm(-1), revealing that no long sequence of intermolecular hydrogen bonding was formed in the LB films at C12 position in contrast with the gels of the same compounds.
  • Hisako Sato, Kenji Tamura, Keishi Ohara, Shin-ichi Nagaoka, Akihiko Yamagishi
    NEW JOURNAL OF CHEMISTRY 35 (2) 394 - 399 1144-0546 2011 [Peer-reviewed]
     Scientific journal 
    The Langmuir-Blodgett films were prepared by hybridizing the clay minerals (synthetic saponite, synthetic hectorite and sodium montmorillonite)with the floating film of a cationic Ir(III) complex, [Ir(ppy)(2)(dc18bpy)](+) (ppy = 2-phenylpyridine; dc18bpy = 4,4'-dioctadecyl-2,2'-bipyridine). When the single-layered hybrid LB film was irradiated at 430 nm, it emitted light in the visible region, whose intensity responded reversibly to the pressure change of oxygen.
  • Hisako Sato, Hidemitsu Uno, Haruyuki Nakano
    DALTON TRANSACTIONS 40 (6) 1332 - 1337 1477-9226 2011 [Peer-reviewed]
     Scientific journal 
    Vibrational circular dichroism (VCD) spectra were measured on the chloroform solutions of a series of mixed-ligand diamagnetic Co(III) complexes, [Co(tfac)(n)(acac)(3-n)] (n = 0-3, tfac = 1,1,1-trifluoro-2,4-pentanedionato; acac = acetylacetonato). Distinct differences were observed in the VCD spectra among the geometrical isomers of the same ligand composition. Such differentiation was hardly possible by their infra-red spectra alone. The structural identification of these isomers was performed in conjunction with DFT calculations.
  • Hisako Sato, Tomoko Yajima, Akihiko Yamagishi
    CHEMICAL COMMUNICATIONS 47 (13) 3736 - 3738 1359-7345 2011 [Peer-reviewed]
     Scientific journal 
    A chiral low-molecular weight gelator, N,N'-diperfluoroheptanoyl-1,29R,R)- or -1,29S,S)-diaminocyclohexane, was prepared to form a gel of acetonitrile. The conformation of the gelator in fibrils was determined by vibrational circular dichroism spectra, providing a molecular model for self-assembly in a helical fibril.
  • Hisako Sato, Aiko Nakao, Akihiko Yamagishi
    NEW JOURNAL OF CHEMISTRY 35 (9) 1823 - 1828 1144-0546 2011 [Peer-reviewed]
     Scientific journal 
    Complex ligands, [Ru(III)(acac)(n)(taetH)(3-n)] (acacH = acetylacetone, taetH(2) = tetraacetylethane), denoted as one-handed and two-handed tectons for n = 2 and 1, respectively, were synthesized and optically resolved. These chiral tectons were reacted with Ni2+ ions in the presence of excess N,N,N',N'-tetramethylethylenediamine (tmen) in methanol or methanol/chloroform. In the case of a one-handed tecton, a trinuclear complex, [{Ru(III)(acac)(2)(taet)}(2)Ni(II)(tmen)], was formed in the ratio of Ni(II)/Ru(III) = 0.5. No chirality was induced in the coordination spheres of labile Ni(II) connectors. In the case of a two-handed tecton, a soluble oligomer, [{Ru(III)(acac)(taet)(2)Ni(II)(tmen)}(n)Ni(II)(tmen)](2+) (n approximate to 4), was produced around Ni(II)/Ru(III) - 1.0 as deduced by XPS analyses and gel chromatography. When the reaction was monitored by electronic circular dichroism, a new peak appeared in the region of 300-400 nm, where the portion of -(taet)Ni(II)(tmen)(taet)- in the oligomers had an electronic absorption. From the vibrational circular dichroism spectra of the same solution, the coordination sphere of a Ni(II) connector was concluded to take a D-or L-configuration preferably, depending on the Lambda- or Delta-configuration of adjacent -(taet) Ru(III)(acac)(taet)- portions, respectively.
  • Yoshiro Kaneko, Hisaya Toyodome, Hisako Sato
    JOURNAL OF MATERIALS CHEMISTRY 21 (41) 16638 - 16641 0959-9428 2011 [Peer-reviewed]
     Scientific journal 
    Ladder-like polysilsesquioxanes containing chiral groups and ammonium chloride groups as side chains were prepared by the polymer reaction method. The chiralities of the resulting PSQs in methanol were induced to the anionic achiral porphyrin such as tetraphenylporphine tetrasulfonic acid (TPPS) while maintaining the monomeric state of TPPS, resulting in the observation of fluorescence emission due to TPPS.
  • Takara Sakurai, Yuichi Masuda, Hisako Sato, Akihiko Yamagishi, Hitoshi Kawaji, Tooru Atake, Kayako Hori
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 83 (2) 145 - 150 0009-2673 2010/02 [Peer-reviewed]
     Scientific journal 
    Chiral and racemic forms of the title compound (12HOAs) were reinvestigated. Gels formed separately from D- and L-12HOAs became a solution containing crystallites on maintaining contact, confirming that DL-12HOA forms no gel, contrary to several reports published over more than ten years, which stated that DL-12HOA formed a gel (for example, P. Terech et al., Langmuir 1994, 10,3406). The powder X-ray diffraction pattern of D-12HOA was different from that of DL-12HOA and the simulated patterns of two crystal structures of DL-12HOA. C-13 NMR spectroscopy for solutions of C6D6 showed significant difference in the concentration dependence of the low-field shifts at the carboxyl C due to hydrogen-bond formation. Analysis based on multiple equilibria among monomer, dimer, and tetramer was successfully applied to the behavior of D-12HOA, but not to that of DL-12HOA. For DL-12HOA, a modified model including hexamer was applied. It is concluded that association of dimers to tetramers and higher aggregates is more favorable in the DL-12HOA solution than in the D-12HOA solution and that D- and L-12HOA molecules recognize each other even in a dilute solution (lower than 2 mmol L-1) of DL-12HOA. Different NMR spectra were also observed in the solid state.
  • Hisako Sato, Dai Shirotani, Kazuaki Yamanari, Sumio Kaizaki
    INORGANIC CHEMISTRY 49 (2) 356 - 358 0020-1669 2010/01 [Peer-reviewed]
     Scientific journal 
    The vibrational circular dichroism (VCD) spectra for Delta-M[Ln((+)-hfbC)(4)] (M(I) = Na, K, Rb, Cs; Ln(III) = La, tu; abbreviated as M-Ln) and Delta-Cs[Yb((+)-hfbC)(4)] (Cs-Yb) were observed in CDCl(3) solutions. The VCD signs and/or intensities are mostly different from those of the Delta-tris(beta-diketonato) transition-metal complexes. The M-Ln complexes give the strong VCD peak(s) near 1550 cm(-1). These VCD patterns are different from each lanthanide(III) complex, but their intensities change with variation of the alkali metal ion. A positive-negative couplet VCD near 1550 cm(-1) for the Delta-M-La complexes is observed similarly for the Delta-tris(beta-diketonato) complexes, confirming the assignment to the Delta absolute configuration based on the exciton CD. The density functional theory calculated VCD for the two peaks at 1650 and 1550 cm(-1) reproduces the relative intensity and signs of the observed ones for the Delta center dot M-La(III) complexes.
  • Hisako Sato, Kenji Tamura, Masahiro Taniguchi, Akihiko Yamagishie
    NEW JOURNAL OF CHEMISTRY 34 (4) 617 - 622 1144-0546 2010 [Peer-reviewed]
     Scientific journal 
    Four members of mixed ligand cyclometalated iridium(III) complexes, fac-[Ir(ppy)(n)L(3-n)] (ppy = 2-phenylpyridine; L = 2-(3-octadecyloxyphenyl)pyridine; n = 0-3), were prepared in a one-pot reaction between [Ir(ppy)(2)(O(boolean AND)O)] (O(boolean AND)O = acetylacetonato) and LH in glycerol at 170 degrees C. Each compound was purified and optically resolved to Delta- and Lambda-enantiomers chromatographically on a chiral column. A film of fac-[Ir(ppy)(n)L(3-n)] floating at an air-water interface was transferred horizontally onto a hydrophobic glass plate as a Langmuir-Blodgett (LB) film. The emission from a single layered LB film was monitored under the atmosphere of various kinds of gases. As a result, molecules with functional groups such as -OH, (sic)C=O and -CN were found to quench efficiently excited fac-[Ir(ppy)(n)L(3-n)] in a film. The effects of isotope and molecular chirality on energy transfer were also investigated, comparing the quenching ability between H(2)O and D(2)O or between R-2-butanol and S-2-butanol on a racemic or chiral film of fac-[Ir(ppy)(2)L], respectively.
  • Noriko Fujimoto, Yukie Mori, Akihiko Yamagishi, Hisako Sato
    CHEMICAL COMMUNICATIONS 46 (30) 5473 - 5475 1359-7345 2010 [Peer-reviewed]
     Scientific journal 
    Star-burst tetranuclear Ru(III) complexes, Delta-(or Lambda-)[{Delta-(or Lambda-)-Ru(III)(acac)(2)(taet)}(3)Ru(III)] (acac = acetylacetonato; taet = tetraacetylethanato), were prepared and resolved into eight enantiomers on a column packed with an ion-exchange adduct of a clay and Delta-[Ru(II)(phen)(3)](2+) (phen = 1,10-phenanthroline), demonstrating that the dual chiralities of the central and peripheral regions were discriminated on the modified clay surface.
  • Mayumi Kudo, Takayuki Hanashima, Atsuya Muranaka, Hisako Sato, Masanobu Uchiyama, Isao Azumaya, Tomoya Hirano, Hiroyuki Kagechika, Aya Tanatani
    J. Org. Chem. 74 (21) 8154 - 8163 1520-6904 2009/11 [Peer-reviewed]
     Scientific journal 
    The oligomeric aromatic ureas bearing N,N'-dimethylated urea bonds such as 3 have aromatic multilayered structure, based on the (cis,cis)-urea structure, and also have dynamic helical structure (all-R or all-S axis chirality) when the benzene rings are connected at the meta positions. The absolute helical structure of oligo(m-phenylurea)s were identified by the empirical and theoretical studies on the CD and vibrational CD (VCD) spectra. Thus, each enantiomer of the oligo(m-phenylurea)s 4 bearing a chiral N-2-(methoxyethoxyethoxy)propyl group were synthesized. Intense dispersion-type CD spectra of 4 were observed, which indicated the induction of handedness in the helical structure. In the VCD spectra of 4 in the film state, the signals due to the carbonyl and aromatic ring vibrations were seen with negative and positive values for compounds 4a and 4b, respectively. The calculations of both CD and VCD spectra of oligo(m-phenylurea)s 3 without any chiral N-substituent gave the same assignment about the axis chirality of 4. Thus, the absolute configurations of 4a and 4b are all-R and all-S structures, respectively.
  • Mayumi Kudo, Takayuki Hanashima, Atsuya Muranaka, Hisako Sato, Masanobu Uchiyama, Isao Azumaya, Tomoya Hirano, Hiroyuki Kagechika, Aya Tanatani
    JOURNAL OF ORGANIC CHEMISTRY 74 (21) 8154 - 8163 0022-3263 2009/11 [Peer-reviewed]
     Scientific journal 
    The oligomeric aromatic ureas bearing N,N'-dimethylated Urea bonds such as 3 have aromatic multilayered Structure, based on the (cis,cis)-urea structure, and also have dynamic helical Structure (all-R or all-S axis chirality) when the benzene rings are connected at the meta positions. The absolute helical structure of oligo(m-phenylurea)s were identified by the empirical and theoretical studies oil the CD and vibrational CD (VCD) spectra. Thus, each enantiomer of the oligo(in-phenylurea)s 4 bearing a chiral N-2-(methoxyethoxyethoxy)propyl group were synthesized Intense dispersion-type CD spectra of 4 were observed, which indicated the induction of handedness in the helical structure. In the VCD spectra of 4 in the film state, the signals due to the carbonyl and aromatic ring vibrations were seen with negative and positive values for compounds 4a and 4b, respectively. The calculations of both CD and VCD spectra of oligo(m-phenylurea)s 3 without my chiral N-substituent gave the same assignment about the axis chirality of 4. Thus, the absolute configurations of 4a and 4b are all-R and all-S structures, respectively.
  • Hisako Sato, Akihiko Yamagishi
    INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES 10 (10) 4559 - 4574 1422-0067 2009/10 [Peer-reviewed]
     
    The Delta- and Lambda-isomerism of octahedral metal complexes is employed as a source of chirality for inducing chiral nematic phases. By applying a wide range of chiral metal complexes as a dopant, it has been found that tris(beta-diketonato) metal(III) complexes exhibit an extremely high value of helical twisting power. The mechanism of induction of the chiral nematic phase is postulated on the basis of a surface chirality model. The strategy for designing an efficient dopant is described, together with the results using a number of examples of Co(III), Cr(III) and Ru(III) complexes with C-2 symmetry. The development of photo-responsive dopants to achieve the photo-induced structural change of liquid crystal by use of photo-isomerization of chiral metal complexes is also described.
  • Mariko Saito, Hisako Sato, Yukie Mori, Yutaka Fukuda
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 82 (10) 1266 - 1273 0009-2673 2009/10 [Peer-reviewed]
     Scientific journal 
    Crystal structures of nickel(II), copper(II), and palladium(II) complexes with (R)-/(S)-2,2'-bis(salicylideneamino)1,1'-binaphthyl were determined. The nickel complex 1 is binuclear consisting of two Ni2+ ions and homochiral two ligand dianions in the crystal. Each Ni2+ ion has a trans-N2O2 square-planar coordination sphere. Either the metal ion or the ligand is less distorted in binuclear complex 1 as compared with the mononuclear copper(II) complex, which has an intermediate structure between square-planar and tetrahedral forms. When dissolved in solvent, complex 1 dissociates into mononuclear species. It is likely that crystallization involves partial ligand-exchange of a mononuclear complex with another molecule of the same chirality to form a homochiral dimer in a self-sorting fashion. Nickel complex with 2,2'-bis(4-methoxysalicylideneamino)-1,1'-binaphthyl (2) forms a 1:1 adduct with (R)-2-(1-hydroxyethyl)pyridine in chloroform solution. The binding constant of (R)-2 is twofold higher than that of (S)-2, which means that the adduct formation proceeds with enantio-differentiation.
  • Hisako Sato, Yukie Mori, Yutaka Fukuda, Akihiko Yamagishi
    INORGANIC CHEMISTRY 48 (10) 4354 - 4361 0020-1669 2009/05 [Peer-reviewed]
     Scientific journal 
    Twenty four kinds of Ru(III) complexes expressed by the formula of Delta- or Lambda-[Ru((-)- or (+)-tfac)(n)(acac)(3-n)] (n = 1, 2, and 3, (-)- or (+)-tfac = (-)- or (+)-3-trifluoroacetylcamphorato and acac = acetylacetonato) were prepared in a pure diastereomeric form. The separation of these diastereomers was accomplished chromatographically by rational use of two antipodal chiral columns. The separated complexes were identified by means of mass spectra, H-1 NMR, electronic circular dichroism, and partly X-ray diffraction analyses. When a pair of Delta- and Lambda-[Ru(acac)(3)] (n = 0) was added to this group, they constituted the complete series of mixed ligand complexes including ligand chirality under the condition of no mixing of chiral ligands. The vibrational circular dichroism (VCD) spectra of their CDCl3 solutions were recorded in the wavenumber region of 1000 similar to 1800 cm(-1). The results provided a benchmark for systematically examining the effects of the stereochemical properties on VCD spectra such as the degree of ligand substitution, Delta Lambda configurations, geometrical isomerism, and ligand chirality. As a result, the geometrical isomers of trans- or cis-[Ru((-)- or (+)-tfac)(2)(acac)] and mer- or fac-[Ru((-)- or (+)-tfac)(3)] were clearly differentiated by their VCD signals, which was hardly possible from their IR spectra alone.
  • Misa Ashizawa, Lifen Yang, Katsuaki Kobayashi, Hisako Sato, Akihiko Yamagishi, Fumio Okuda, Takunori Harada, Reiko Kuroda, Masa-aki Haga
    DALTON TRANSACTIONS (10) 1700 - 1702 1477-9226 2009 [Peer-reviewed]
     Scientific journal 
    Optically resolved blue-phosphorescent iridium complexes bearing 1-(2-pyridyl)-3-(N-methylimidazol-2-yl)-4,6-difluorobenzene (LH) as an asymmetric tridentate ligand exhibited opposite circularly polarized luminescence (CPL) spectra.
  • Tsuneomi Kawasaki, Toshiki Omine, Kenta Suzuki, Hisako Sato, Akihiko Yamagishi, Kenso Soai
    ORGANIC & BIOMOLECULAR CHEMISTRY 7 (6) 1073 - 1075 1477-0520 2009 [Peer-reviewed]
     Scientific journal 
    The synthetic hectorite containing intercalated chiral Delta and Lambda-tris(1,10-phenanthroline) ruthenium(II) ions acts as a heterogeneous chiral catalyst in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde to afford, in combination with asymmetric autocatalytic amplification of enantiomeric excess, 5-pyrimidyl alkanol with high enantiomeric excess.
  • Hisako Sato, Kenji Tamura, Masahiro Taniguchi, Akihiko Yamagishi
    CHEMISTRY LETTERS 38 (1) 14 - 15 0366-7022 2009/01 [Peer-reviewed]
     Scientific journal 
    A cationic iridium(III) complex, [Ir(ppy)(2)dmbpyl] (ppy = 2-phenylpyridine and dmbpy = 4,4'-dimethylbipyridine), was adsorbed by colloidally dispersed montmorillonite clay. The emission quantum yield (Phi) decreased from 0.06 to 0.01 on adsorption, while Phi recovered to ca. 0.12 by adding alkali or alkaline earth metal ions to the concentration of ca. 2 x 10(-2) or 2 x 10(-5) M, respectively.
  • Yasutaka Suzuki, Ryoya Matsunaga, Hisako Sato, Toshihiro Kogure, Akihiko Yamagishie, Jun Kawamata
    CHEMICAL COMMUNICATIONS (45) 6964 - 6966 1359-7345 2009 [Peer-reviewed]
     Scientific journal 
    SHG measurements on a highly transparent clay film ion-exchanged with chiral metal complexes revealed that the mono-molecular layer of the chiral complexes in an interlayer space acquired a non-centrosymmetric character.
  • Hisako Sato, Kayako Hori, Takara Sakurai, Akihiko Yamagishi
    CHEMICAL PHYSICS LETTERS 467 (1-3) 140 - 143 0009-2614 2008/12 [Peer-reviewed]
     Scientific journal 
    Vibrational circular dichroism (VCD) spectra were recorded on a benzene-d(6) gel sample of R- or S-12-hydroxyoctadecanoic acid (denoted by R- or S-12-HOA, respectively). The observed peaks were well reproduced by the theoretical calculation carried out for the optimized conformation of a 12-HOA molecule. The strong bisignate peaks assigned to the stretching vibrations of C=O bond in a carboxylic group were rationalized in terms of the model that two 12-HOA molecules formed a dimer through hydrogen bonding in a bent conformation. (C) 2008 Elsevier B.V. All rights reserved.
  • Jun Yoshida, Hisako Sato, Naomi Hoshino, Akihiko Yamagishi
    JOURNAL OF PHYSICAL CHEMISTRY B 112 (32) 9677 - 9683 1520-6106 2008/08 [Peer-reviewed]
     Scientific journal 
    Two kinds of tris(beta-diketonato) metal(III) complexes denoted as [M(acac)(2)(LC12)] and [M(acac)(2)(L-azo)] (M = Ru(III) and Co(III); acac = acetylacetonato; LC12 = 1,3-didodecyloxyphenyl-1,3-propanedionato; L-azo = 3-[4'-(4 ''-(butoxy)phenylazo)phenyl]-pentane-2,4-dionato) were synthesized and optically resolved into A, A isomers. Here, LC12 and L-azo were designed to be elongated perpendicular to and in parallel with the molecular C-2 axis, respectively. The metal complexes were doped into three kinds of nematic liquid crystals (MBBA, EBBA, and ZLI-1132). Both dopants induced chiral nematic phases with relatively high helical twisting powers. With a purpose to clarify the mechanisms of helical induction, order parameters (S) were determined by means of polarized UV-vis measurements on nematic samples doped with racemic Co(III) complexes. As a result, the long axes of the elongated ligands in both [Co(acac)(2)(LC12)] and [Co(acac)(2)(trans-L-azo)] were found to align in the direction of the director vector with S = 0.50 +/- 0.05 and 0.60 +/- 0.05, respectively. Based on the results, the photoresponsive behavior of Delta- or Lambda-[Ru(acac)(2)(L-azo)] was interpreted in terms of the variation of S accompanied with the cis-trans isomerization of the azobenzene moiety in L-azo.
  • Hisako Sato, Jun Kameda, Yutaka Fukuda, Masa-aki Haga, Akihiko Yamagishi
    CHEMISTRY LETTERS 37 (7) 716 - 717 0366-7022 2008/07 [Peer-reviewed]
     Scientific journal 
    A chiral tri-nuclear metal complex, Delta Delta Delta- or Lambda Lambda Lambda-[Ru(acac)(2)(taet)Ru(acac)(taet)Ru(acac)(2)] (acac = acetylacetonato and taet = tetraacetylethanato), was prepared and its monolayer behavior was investigated, leading to the conclusion that the bead-like character of the trimer was an essential factor in achieving stable two-dimensional molecular packing.
  • Hisako Sato, Kentaro Okamoto, Kenji Tamura, Hirohisa Yamada, Kazuko Saruwatari, Toshihiro Kogure, Akihiko Yamagishi
    APPLIED PHYSICS EXPRESS 1 (3) 0350011 - 0350013 1882-0778 2008/03 [Peer-reviewed]
     Scientific journal 
    A heterojunction photodiode was fabricated by forming two contact regions on a glass substrate: one side was a cast film of perovskite-type niobate [(CH(3))(3)NHSr(2)Nb(3)O(10)] as a n-type photosemiconductor and the other side a cast film of Zn-saponite (Na(0.96)[Si(7.18)Al(0.64)]Zn(6.20)O(20)-(OH)(2)) as a p-type semiconductor under oxygen atmosphere. Diode-type current-voltage characteristics were obtained under the illumination of light (340 nm) and oxygen atmosphere (1 atm) at 25-100 degrees C. The interfacial structure was studied by means of focused ion-beam and transmission electron microscopy techniques, confirming the contact of the two different nanosheets on a nanometer scale. The results are discussed on the basis of the nanosheet band structures. (C) 2008 The Japan Society of Applied Physics.
  • Hisako Sato, Yuka Furuno, Yutaka Fukuda, Kentaro Okamotob, Akihiko Yamagishi
    DALTON TRANSACTIONS (10) 1283 - 1285 1477-9226 2008 Scientific journal 
    The central labile Al(III) core of a star-shaped tetra-nuclear metal complex, [{Delta-Ru(III)(acac)(2)(taet)}(3)Al(III)] (acac = acetylacetonato; taet = tetraacetylethanato), which was synthesized by reacting Delta-[Ru(III)(acac)(2)(taetH)] (taetH = singly protonated taet) with an Al(III) ion in solution, was found to be locked as a Lambda-form in the solid state.
  • Hisako Sato, Yuka Furuno, Yutaka Fukuda, Kentaro Okamotob, Akihiko Yamagishi
    DALTON TRANSACTIONS (10) 1283 - 1285 1477-9226 2008 [Peer-reviewed]
     Scientific journal 
    The central labile Al(III) core of a star-shaped tetra-nuclear metal complex, [{Delta-Ru(III)(acac)(2)(taet)}(3)Al(III)] (acac = acetylacetonato; taet = tetraacetylethanato), which was synthesized by reacting Delta-[Ru(III)(acac)(2)(taetH)] (taetH = singly protonated taet) with an Al(III) ion in solution, was found to be locked as a Lambda-form in the solid state.
  • Hisako Sato, Akihiko Yamagishi
    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 8 (2) 67 - 84 1389-5567 2007/10 [Peer-reviewed]
     Scientific journal 
    Photochemical studies on the use of chiral metal complexes in homogenous and heterogeneous systems are surveyed and commented on their significance. A main focus is laid on the utility of the AA isomerism of octahedral metal complexes as a chiral source. The reported works demonstrate that chiral metal complexes are effective as a molecular element in achieving varieties of functions such as chiral discrimination, chiral transfer, sensing and photoresponsive guests for biomolecules or liquid crystals. (c) 2007 Elsevier B.V. All rights reserved.
  • Takeshi Hashimoto, Yuji Kawamoto, Yousuke Ishitobi, Tatsuya Sasaki, Yutaka Fukuda, Akihiko Yamagishi, Hisako Sato, Kunio Shimizu, Takashi Hayashita
    CHEMISTRY LETTERS The Chemical Society of Japan 36 (9) 1174 - 1175 0366-7022 2007/09 [Peer-reviewed]
     Scientific journal 
    Symmetric alkoxide-bridged diruthenium complexes [{Ru(acac)(2)}(2)(mu-OMe)(2)], which are obtained when [Ru(acac)(2)(CH3CN)(2)] reacts in methanol, can be separated into two diastereomers by column chromatography, and these diastereomers are found to exhibit different magnetic properties despite their structural similarities.
  • Hisako Sato, Tohru Taniguchi, Atsufumi Nakahashi, Kenji Monde, Akihiko Yamagishi
    INORGANIC CHEMISTRY 46 (16) 6755 - 6766 0020-1669 2007/08 [Peer-reviewed]
     Scientific journal 
    Vibrational circular dichroism (VCD) spectra of a series of [M(III)(acac)(3)] (acac = acetylacetonato; M = Cr, Co, Ru, Rh, Ir, and Al) and [M(III)(acac)(2)(dbm)] (dbm = dibenzoylmethanato; M = Cr, Co, and Ru) have been investigated experimentally and/or theoretically in order to see the effect of the central metal ion on the vibrational dynamics of ligands. The optical antipodes give the mirror-imaged spectra in the region of 1700-1000 cm(-1). The remarkable effect of the central metal ion is observed experimentally on the VCD peaks due to C-O stretches (1500-1300 cm(-1)) for both [M(III)(acac)(3)] and [M(III)(acac)(2)(dbm)]. In the case of Delta-[M(III)(acac)(3)], for example, the order of frequency of two C-O stretches (E and A(2) symmetries) is dependent on the kind of a central metal ion as follows: E (-) > A(2) (+) for M = Co, Rh, and Ir, while A(2) (+) > E (-) for M = Cr and Ru. In the case of Delta-[M(III)(acac)(2)(dbm)], the order of frequency of three C-O stretches (A, B, and B symmetries) is as follows: A (-) > B (+) > B (+) for Co(III), B (+) > A (-) > B (-) for Cr(III), and A (-) > B (+) > B (-) for Ru(III). These results imply that the energy levels of C-O stretches are delicately affected by the kind of central metal ion. Since such detailed information is not obtained from the IR spectra alone, the VCD spectrum can probe the effect of the central metal ion on interligand cooperative vibration modes.
  • Kentaro Okamoto, Hisako Sato, Kazuko Saruwatari, Kenji Tamura, Jun Kameda, Toshihiro Kogure, Yasushi Umemura, Akihiko Yamagishi
    JOURNAL OF PHYSICAL CHEMISTRY C 111 (34) 12827 - 12833 1932-7447 2007/08 [Peer-reviewed]
     Scientific journal 
    A thin film of trimethylammonium-exchanged perovskite-type niobate ((CH3)(3)NHSr2Nb3O10) was prepared by casting its exfoliated aqueous dispersion onto a glass substrate. The electric conductivity of a film (3-9 mu m thick) was measured in vacuum under the illumination of light (280 similar to 450 nm). Photocurrent raised and decayed slowly in the time range of 10(3) seconds in response to the on-and-off of an incident light. Atmospheric oxygen accelerated the decay rate of current in the dark. In the absence of oxygen, the decay curve obeyed the equation of stretched exponential relaxation (i(p) = i(p)(0) exp(-(t/tau)(beta)). From the dependence of the photocurrent on various parameters such as film thickness, light wavelength, and temperature, the observed persistent phenomena were interpreted according to the following mechanisms: (1) a free electron was photogenerated under the illumination of light most effectively when photon energy corresponded to the edge of a band gap transition; (2) the generated electrons were trapped at surface oxygen vacancies before they became conductive; and (3) a persistent current appeared through the multistep trapping-detrapping processes under the gradient of electric field. It was suggested that vacancies were produced by the elimination of lattice oxygen atoms as dianions during the acid treatment of original niobate (KSr2Nb3O10). As far as we know, the present finding is the first example of persistent photocurrents in inorganic thin films.
  • Yuka Furuno, Hisako Sato, Jun Yoshida, Naomi Hoshino, Yutaka Fukuda, Akihiko Yamagishi
    JOURNAL OF PHYSICAL CHEMISTRY B 111 (3) 521 - 526 1520-6106 2007/01 [Peer-reviewed]
     Scientific journal 
    The linkage effects of polynuclear metal complexes on chiral induction have been studied by application of the chiral oligomers of acetylacetonato chromium(III) units as a dopant, inducing chiral nematic phases. The compounds were prepared by reacting [Cr(acac)(3)] (acac = acetylacetonato) and 1,1,2,2-tetraacetylethane (taetH(2)) in solid phase at 160 degrees C. Binuclear diastereomers were separated on a silica gel column, followed by chromatographic resolution on a chiral column packed with an ion-exchange adduct of Delta-[Ru(phen)(3)](2+) (phen = 1,10-phenanthroline) and synthetic hectorite. An enantiomeric pair (Delta Delta- and Lambda Lambda-[Cr(acac)(2)(taet)Cr-(acac)(2)]) and a meso species (Delta Lambda-[Cr(acac)(2)(taet)Cr(acac)(2)]) were identified. The binuclear enantiomers were doped into a room-temperature nematic liquid crystal, N-methoxybenzylidene-4-n-butylaniline. Helical twisting power (beta(M)) was found to be +97.9 and -88.9 mu m(-1) for Lambda Lambda- and Delta Delta-[Cr(acac)(2)(taet)Cr(acac)(2)], respectively. The values were compared with beta(M) for the monomeric enantiomers (+99.5 and -91.0 mu m(-1) for Lambda- and Delta-[Cr(acac)(3)], respectively). The results are interpreted on the basis of the surface chirality model. Delta Delta-[Cr(acac)(2)(taet)Cr(acac)(2)] was found to photoisomerize both in a hexane solution and in a liquid crystal phase of ZLI-1132. The quantum yield of photoisomerization in a liquid crystal phase was lowered to ca. 30% of that in a hexane solution.
  • Jun Yoshida, Kazuko Saruwatari, Jun Kameda, Hisako Sato, Akihiko Yamagishi, Laisheng Sun, Maria Corriea, Gilles Villemure
    LANGMUIR 22 (23) 9591 - 9597 0743-7463 2006/11 [Peer-reviewed]
     Scientific journal 
    Hybrid films composed of amphiphilic molecules and clay particles were constructed by the modified Langmuir-Blodgett (LB) method. Clays used were sodium montmorillonite (denoted as mont) and synthetic smectite containing Co(II) ions in the octahedral sites (denoted as Co). Two kinds of amphiphilic molecules were useds[Ru(dC(18)bpy)( phen)(2)](ClO4)(2) (dC(18)bpy)4,4'-dioctadecyl-2,2-bipyridyl and phen = 1,10-phenanthroline) (denoted as Ru) and octadecylammonium choloride (ODAH(+) Cl- or denoted as ODAH). Three kinds of hybrid films (denoted as Rumont, Ru-Co, and ODAH-Co films) were prepared by spreading an amphiphilic molecule onto an aqueous suspension of a clay. Atomic force microscopy (AFM) analyses of the films deposited on silicon wafers indicated that closely packed films were obtained at 20 ppm for all the above three cases. Cyclic voltammetry (CV) was measured on an ITO electrode modified with a hybrid film or a monolayer film of pure Ru(II) complex salt (denoted as Ru film). The Ru( II) complexes incorporated in the Ru-mont film lost their redox activity, indicating that montmorillonite layers acted as a barrier against electron transfer. In contrast, the same complexes in the Ru-Co film were electrochemically active with the simultaneous appearance of the redox peaks due to the Co(II)/Co(III) (or Co(II)/ Co(IV))couple. The results implied that electron transfer through cobalt clay layers was possible via mediation by Co( II) ions in a clay sheet. For an aqueous solution containing nitrite ions (NO2-) at pH 3.0, a large catalytic oxidation current was observed for both the electrodes modified with the Ru-mont and Ru-Co films. The results were interpreted in terms of the mechanisms that the charge separation of an incorporated Ru(II) complex took place to produce a pair of a Ru(III) complex and an electron and that the generated Ru(III) complex was reduced by a nitrite ion before it recombined with the electron.
  • Kazuko Saruwatari, Hisako Sato, Toshihiro Kogure, Takayuki Wakayama, Masanori Iitake, Kosho Akatsuka, Masaaki Haga, Takayoshi Sasaki, Akihiko Yamagishi
    LANGMUIR 22 (24) 10066 - 10071 0743-7463 2006/11 [Peer-reviewed]
     Scientific journal 
    Electrical conductivity of titania nanosheets was investigated for a single-layered Langmuir-Blodgett (LB) film deposited onto a comb-type electrode (5 or 10 mu m(electrode spacing) x 8 mm (electrode width)). The photoresponsive electrical properties of the film were investigated by irradiating with a Xe lamp under various atmospheric conditions. The atmosphere was controlled by introducing either oxygen or nitrogen gases containing different amounts of water vapor. As a result, the LB film behaved as an insulator with little photoresponse under dry atmospheric conditions. It became conductive on illuminating with a Xe lamp under a wet oxygen atmosphere. Conductivity increased with the increase of irradiation time (0-30 min) to attain a stationary value in 1 h. The highest conductive state thus attained lasted for several hours in the dark. The impedance of the film was measured over the frequency range of 1 MHz to 50 Hz by varying the relative humidity of an atmosphere from 0 to 100%. The results were analyzed by assuming an equivalent circuit consisting of one resistance (R) with constant Warburg component (W) and one capacitance (C) in parallel. The R component depended remarkably on the relative humidity, while the C component stayed nearly at the constant value. The dependence of R on water vapor (P-H2O) was expressed by R = A[P-H2O](n) with A = constant and n = -2.9. The results were rationalized in terms of the surface modification of titania nanosheets to hydrophilic nature under the illumination of UV light.
  • Tadashi Mitsuoka, Hisako Sato, Jun Yoshida, Akihiko Yamagishi, Yasuaki Einaga
    CHEMISTRY OF MATERIALS 18 (15) 3442 - 3447 0897-4756 2006/07 [Peer-reviewed]
     Scientific journal 
    We have attempted to control the helical pitch of a chiral nematic liquid crystal by the use of a photoresponsive chiral metal complex. For this purpose, a novel Ru(III) complex [Ru(acac)(2)(L)] was synthesized, where acac and L denote acetylacetonato and 1,3-bis-{4-[6-(4-phenylazo-phenoxy)-hexyloxy]-phenyl}-propane-1,3- dionato, respectively. The complex underwent cis-trans photoisomerization in methanol when under UV (lambda(max) = 360 nm) or visible (lambda(max) = 450 nm) light illumination, respectively. When the complex was doped into a room-temperature nematic liquid crystal (ZLI-1132), it induced a chiral nematic phase. Under illumination with UV or visible light, the helical pitch of the chiral nematic phase could be changed reversibly by up to 50%. Corresponding to this change, the helical twisting power (HTP) of the complex varied between 34.0 and 22.0 mu m(-1), or between -43.9 and -26.6 mu m(-1) at 35.0 degrees C, where the positive and negative signs corresponded to the Lambda- and Delta-enantiomers, respectively. This has been the first attempt at combining the Delta Lambda chirality of an octahedral metal complex with the cis-trans isomerization of an azobenzene group in the development of a photoresponsive dopant.
  • Hisako Sato, Tohru Taniguchi, Kenji Monde, Shin-Ichiro Nishimura, Akihiko Yamagishi
    CHEMISTRY LETTERS 35 (4) 364 - 365 0366-7022 2006/04 [Peer-reviewed]
     Scientific journal 
    The VCD spectra of a series of tris(acetylacetonato)metal(III) ([M(acac)(3)] with M = Co, Cr, Ru, and Rh) have revealed a new aspect concerning the effects of a central metal ion on the vibrational energy levels split by the inter-ligand interactions. Our present view is that the correlated vibrational motions of vicinal ligands are affected by the d-electron configuration of a central metal ion.
  • S Fujita, H Sato, N Kakegawa, A Yamagishi
    JOURNAL OF PHYSICAL CHEMISTRY B 110 (6) 2533 - 2540 1520-6106 2006/02 Scientific journal 
    The present work pursued a possibility that enantioselectivity was achieved through weak intermolecular interactions between a catalyst and a substrate. For that purpose, we Studied the photooxidation of alpha-ethylbenzyl phenyl sulfide catalyzed by a polypyridyl ruthenium(II) complex as a chiral photosensitizer. No covalent bonding was formed between a catalyst and a substrate, because the complexes used ([Ru(phen)(3)](2+) or [Ru(bpY(3))(2+)]) were coordinatively saturated. Enantiomer excess (ee) was attained to be 30% when a chiral photosensitizer was immobilized on montmorillonite clay. It was even improved to 43% in the presence of an additional chiral auxiliary, dibenzoyl-(D)(+)-tartaric acid. Notably, no enantioselectivity was achieved when the reaction took place in homogeneous solutions. The ab initio calculations were performed on the stability of an associate composed of a catalyst (metal complex) and a product (sulfoxide) to obtain a clue to reaction mechanisms. The calculations suggest that chiral discrimination is achieved even through noncovalent interactions between a substrate and a chiral senstizer when the attacking direction by a substrate toward a catalyst is limited sterically on a solid surface.
  • Tohru Taniguchi, Kenji Monde, Shin-Ichiro Nishimura, Jun Yoshida, Hisako Sato, Akihiko Yamagishi
    MOLECULAR CRYSTALS AND LIQUID CRYSTALS 460 107 - 116 1542-1406 2006 [Peer-reviewed]
     Scientific journal 
    Vibrational circular dichroism (VCD) spectroscopy has been applied for monitoring in situ the photoinduced rewind of supramolecular helices in a liquid crystal. The monitored system was a room.-temperature liquid crystal, ZLI-1132, doped with a novel chiral Cr(III) complex. Under the illumination of UV light, (365nm), the photoracemization of the Cr(III) complex led to the rewind of helices in the chiral nematic phase. In, response to this, the VCD spectrum of the system exhibited the transient change, confirming the elongation of helical pitch length. The possibility of using the VCD spectrum as a memory of photoresponsive events is discussed.
  • H Sato, K Ono, CT Johnston, A Yamagishi
    AMERICAN MINERALOGIST 90 (11-12) 1824 - 1826 0003-004X 2005/11 Scientific journal 
    The mechanical behavior of minerals under high pressure has attracted considerable interest in recent years. Clay minerals, including kaolinite, are common minerals found in sedimentary environments and their behavior under pressure is an important factor in understanding seismogenic zones. Kaolinite is a ubiquitous member of the kaolin group of 1:1 phyllosilicates that have recently been found to undergo a structural phase transition between 2.0 and 2.5 GPa. In this study, the bulk modulus and elastic constants of kaolinite have been calculated from first principles within density functional theory (DFT) for the first time. The bulk modulus is predicted to be 23 GPa for kaolinite. The calculated elastic constant tensors indicate that the a direction is slightly more flexible than the b direction. The calculated elastic constant tensor along c is much lower than the constants calculated along a and b consistent with the crystal structure of kaolinite. Elastic wave velocities for P- and S-waves were calculated to be 7.34 and 3.50 km/s, respectively. Since an agreement between the theoretical and experimental values is satisfactory, we conclude that the theoretical calculations presented here are useful in seismic research for predicting the mechanical properties of minerals that are difficult to obtain experimentally because of their small particle size (typically <2 micrometers).
  • Y Matsuoka, H Sato, A Yamagishi, K Okamoto, N Hoshino
    CHEMISTRY OF MATERIALS 17 (20) 4910 - 4917 0897-4756 2005/10 Scientific journal 
    A high-power chiral dopant system involving 6-coordinate metal complexes was designed on the basis of a shape model. Accordingly, a series of mixed 1,3-diketonate complexes of Ru(III), [Ru(acac)(2)(L-n)], in which acac = acetylacetonate and L-n = dibenzoylmethanate substituted with n octyloxy groups (abbreviated as Ru-n hereafter), was prepared and optically resolved. Their performance as chiral dopants was evaluated in terms of helical twisting power (HTP) in a room-temperature nematic liquid crystal, N-(4-methoxybenzylidene)-4-n-butylaniline (MBBA), by measuring the helical pitch lengths and CD spectra for the induced chiral nematic phases. The Delta- and Lambda-enantiomers induced macroscopic lefthanded (M) and right-handed (P) helices, respectively, and the (absolute) values for HTP have proven to be remarkably large, e.g. beta(M) = 1.8 x 102 mu m(-1) in the case of Lambda-Ru-2. The induced CD spectra for the dilute MBBA* materials (the asterisk denotes in this paper that MBBA has been doped with a chiral substance) were fit to the interpretation that persistent helical alignment of host molecules was generated. We also performed quantum chemical calculations for the optimum configuration of model Al(III) complexes with and without MBBA molecules and found that two liquid crystal molecules will eventually form a negative dihedral angle (left-handed twist) over the Delta-enantiomer of dialkylated complex.
  • H Sato, Y Hiroe, K Tamura, A Yamagishi
    JOURNAL OF PHYSICAL CHEMISTRY B 109 (40) 18935 - 18941 1520-6106 2005/10 Scientific journal 
    The present work reports an attempt to elucidate a stereoselective energy-transfer system by immobilizing a chiral metal complex on a clay surface. The metal complex used was [Ru(bpY)(2)L-i](2+) with L, = bpy (2,2'-bipyridine), L-2 = 4,4'-diundecyl-2,2'-bipyridine, and L-3 = 5,5'-diundecyl-2,2'-bipyridine. The adsorption structure of [Ru(bpy)(2)Li](2+) was studied by means of electric dichroism measurements on an aqueous dispersion of a colloidal clay. It was found that the molecular orientation of the adsorbed Ru(II) complex was affected remarkably by the positions of the alkyl chains on the bpy ligand; that is, the angle of the 3-fold or pseudo-3-fold symmetry axis of the Ru(II) complex with respect to the surface normal was obtained to be 24 degrees, 30 degrees, and 52 degrees for i = 1, 2, and 3, respectively. The efficiency of the energy-transfer was determined by photoluminescence quenching measurements between the adsorbed Ru(II) complex and [Ru(acac)(3)] (acac = acetylacetonate) in solution. As a result, stereo selectivity appeared most for the case of [Ru(bpy)(2)L-3](2+) in which its two helically twisted bpy ligands were projected in an outward direction.
  • H Sato, A Yamagishi, J Yoshida, H Nakano, N Hoshino
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 44 (6A) 4067 - 4072 0021-4922 2005/06 Scientific journal 
    A computational approach to the evaluation of helical twisting powers (HTP) of chiral metal complexes of [Ru(blade)(2)(backbone)] type is presented. The dopant contains helically attached "blade" ligands and an elongated "backbone" ligand, and some remarkably powerful examples have been reported. In this work, the observed HTP is interpreted in terms of a microscopic interaction of a dopant and host molecules with atomistic details. For this purpose, the stable structure of a triad system comprising a dopant and two host molecules was obtained by geometry optimization using Gaussian03. As a result, the host molecules interacted attractively with the dopant, being twisted in the same direction as observed experimentally. Interaction energy was assessed as a function of the dihedral angle between the two host molecules, leading to a quadratic dependence with a minimum at the equilibrium twisting angle of -32 degrees. Based on this, the expression was derived, in which helical twisting power was given in terms of the equilibrium twisting angle of a pair of strongly interacting host molecules.
  • J Yoshida, H Sato, A Yamagishi, N Hoshino
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 127 (23) 8453 - 8456 0002-7863 2005/06 Scientific journal 
    It is demonstrated that the sign of helical twisting power (HTP) of an enantiomeric Ru(III) complex of type [Ru(acac)(2)L] can be switched by choosing L from either L-per or L-para, which is elongated either perpendicular or parallel to the C-2 symmetry axis, and four states become available in combination with Delta Lambda-chirality of the metal center. Complexes 1-n, in which 4,4'-dialkoxylated dibenzoylmethanate ligands are used as L-per, and 2 having L-para = 3-(4'-decyloxyphenyl)pentane-2,4-dionate ligand were prepared for this purpose. They were optically resolved into the enantiomers by means of a clay column chromatography, and their performance as chiral dopants was evaluated in nematic liquid crystals including a room-temperature system, N-methoxybenzylidene-4-n-butylaniline (MBBA), which allowed facile measurements of the helical pitch lengths and CID spectra in the induced chiral nematic states. The induced CID signals have provided a clear evidence for the helical inversion between the two structure types, 1 and 2, of the same chirality. The twisting power of these six-coordinate metal complexes and their structure versus twist sense correlations are interpreted by the shape model. Intrinsically high HTP of Delta-[Ru(acac)(2)L-per] has also allowed for observation of the pitch band due to the selective reflection in the visible wavelength range at the doping level of 2 mol % in MBBA.
  • K Saruwatari, H Sato, T Idei, J Kameda, A Yamagishi, A Takagaki, K Domen
    JOURNAL OF PHYSICAL CHEMISTRY B 109 (25) 12410 - 12416 1520-6106 2005/06 Scientific journal 
    A hybrid film of layered niobate and an organic amphiphile was prepared by the Langmuir-Blodgett (LB) method. Trimethylammonium-exchanged perovskite-type niobates ((CH3)(3)NHSr2Nb3O10) were exfoliative to form an aqueous suspension. A monolayer of octadecylamine was produced on such an aqueous dispersion as a template for a hybrid film. A hybrid film was transferred as a Y-type LB film onto a hydrophilic glass plate or an ITO substrate. The structure of a deposited film was investigated with X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and atomic force microscopy (AFM) measurements, indicating a layer-by-layer structure with a single or double sheet of niobate as an inorganic composite. From the cyclic voltammogram on an ITO electrode modified with the Y-type 10 layered film, the lower edge of the conduction band of a niobate layer was determined to be - 0.6 V (vs Ag/AgCl). ac impedance and dc measurements were carried out on 1, 5, and 10-layered LB films (2 mm (electrode spacing) x 8 mm (width)) with aluminum electrodes. The freshly deposited samples behaved as an insulator under the illumination of 280 nm light (2.04 x 10(16) quanta s(-1)). Photoconductivities appeared, however, when they were preirradiated with a 150 W Xe lamp (ca. 2 x 10(18) quanta s(-1)) for 0.5-8.5 h. The process was denoted as photomodification. From the FT-IR and XRD results, it was deduced that the photomodification of LB films caused the decomposition of organic templates (octadecylammonium) accompanied by the collapse of layer-by-layer structures. dc analyses on the 5- and 10-layered films after photomodification also showed that they behaved as a photosemiconductor under UV light illumination.
  • K Saruwatari, H Sato, J Kameda, A Yamagishi, K Domen
    CHEMICAL COMMUNICATIONS (15) 1999 - 2001 1359-7345 2005/04 Scientific journal 
    By measuring the photoconductivity of hybrid LB films of exfoliative layered niobate and octadecylamine, it was evidenced that the film underwent a transition from an insulator to a photosemiconductor during photo-modification treatment by UV fight, which was rationalized in terms of the direct contact of inorganic nanosheets achieved by the elimination of organic layers.
  • JX He, H Sato, Y Umemura, A Yamagishi
    JOURNAL OF PHYSICAL CHEMISTRY B 109 (10) 4679 - 4683 1520-6106 2005/03 Scientific journal 
    A chiral sensing electrode has been prepared by coating an indium tin oxide (ITO) substrate with a hybrid film of metal complexes and a clay layer (montmorillonite). By applying the combined method of the Langmuir-Blodgett and self-assembly techniques, a monolayer of a water-soluble chiral metal complex (A[Os(phen)3] 21), which acted as a mediator of oxidizing a target molecule, was fixed electrostatically onto a single-layered clay film. Chiral sensing was demonstrated by monitoring a photocurrent when the electrode was in contact with an aqueous NaClO4 solution of 1,1 '-2-binaphthol. As a result, the S-1,1 '-2-binaphthol gave a photocurrent 1.8 times higher than the R-isomer at the applied potential of 700 mV (vs Ag vertical bar AgCl vertical bar KCl-(sat)). Detection limit was determined to be 40 mu M from the concentration dependence of a response current. Mechanisms for chiral sensing effect were explained in terms of the stereoselective binding of 1,1 '-2-binaphthol with adsorbed Lambda-[Os(phen)(3)](2+) on a clay surface.
  • K Kobayashi, H Sato, S Kishi, M Kato, S Ishizaka, N Kitamura, A Yamagishi
    JOURNAL OF PHYSICAL CHEMISTRY B 108 (48) 18665 - 18669 1520-6106 2004/12 Scientific journal 
    When a chloroform solution of a dicyano(diimine)platinum(II) complex, [Pt(CN)(2)(5,5'-dinonyl-2,2'-bipyfidine)], was spread onto pure water, a reversible surface pressure- molecular area curve was obtained. The surface pressure began to increase steeply from 0 at a molecular area of 0.61 nm(2) molecule'. On further compression, the iTionolayer was stable at 0.2 nm(2) molecule' and 30 mN m(-1). In such a highly compressed state, the complex was thought to orient its planar ligand 2,2'-bipyridine perpendicular to the water surface. The floating monolayer was vertically deposited onto a hydrophobic quartz substrate as an X-type film. The absorption spectra of the deposited filins showed a broad peak at 480 nm, while that band was absent in the solution spectrum. The emission spectra of the films exhibited a broad band around 600 nm. The excitation spectra monitored at 600 nm coincided well with the absorption spectra. The results were interpreted in terms of the formation of the molecular aggregate, in which the platinum complexes were stacked with the overlaying bipyridine moieties. In such an aggregate, the MMLCT state was generated due to the Pt-Pt interaction among the neighboring molecules. On the basis of the model, the absorption band at 480 nm and the emission band at 600 nm were assigned to the (MMLCT)-M-1 and (MMLCT)-M-3 transitions from or to the dsigma* orbital of Pt(II) to or from the pi* orbital of 2,2'-bipyridine, respectively. The AFM observation showed that the film deposited on a silicon wafer consisted of a grain-shaped aggregate, assisting the intermolecular interactions of composite molecules.
  • H Sato, K Ono, CT Johnston, A Yamagishi
    AMERICAN MINERALOGIST 89 (11-12) 1581 - 1585 0003-004X 2004/11 Scientific journal 
    The polytype structures of the three 1:1 dioctahedral phyllosilicates found in nature, kaolinite, dickite, and nacrite, have been investigated, using first-principle calculations within density functional theory. The crystal structures were calculated by being optimized with relaxation of all atomic positions. The calculated structural parameters, including the orientation of the OH groups, for the three polytypes are in good agreement with experimental data. In particular, for kaolinite and dickite, the three-inner surface OH groups were predicted to be oriented nearly perpendicular to the (001) plane. In contrast, one of the inner surface OH groups of nacrite was predicted to be nearly parallel with respect to the (001) plane. Based on a comparison of formation energies, the chiral polymorphs of kaolinite (B- or C-site vacancy) have similar formation energies as dickite and nacrite, while achiral kaolinite with A-site vacancy is only slightly less stable than the other polytypes.
  • H Sato, Y Hiroe, T Sasaki, K No, A Yamagishi
    JOURNAL OF PHYSICAL CHEMISTRY B 108 (45) 17306 - 17312 1520-6106 2004/11 Scientific journal 
    Electric dichroism measurements have been performed on an aqueous dispersion of unilamellar titanium oxides produced by the exfoliation of the following three kinds of titanium oxides: (A) lepidocrocite-type titanate (Cs(0.7)Ti(1.825)square(0.175)O(4)), (B) tetratitanate (K2Ti4O9), and (C) pentatitanate (Cs2Ti5O11). The AFM images showed that these exfoliated titanium oxides consisted of flakelike particles with an average diameter ranging from 0.1 to 2 mum. Under the applied voltage pulse [(1-20) x 10(3) V cm(-1)], an aqueous dispersion of titanium oxides exhibited orientational dichroism in the UV region with a maximum around 300 nm. From the reduced linear dichroism at complete orientation, the orientation of the effective transition moment (mu(eff)) was determined with respect to the oriented axis of a particle. Here mu(eff) was defined as the vector sum of three orthogonal transition moments of a particle. As a result, an angle (alpha) between mu(eff) and the oriented axis of a particle was determined to be alpha = 41.6degrees, 24.6degrees, and 23.6degrees at 300 nm for samples A-C, respectively. The results were compared with the recent theoretical calculations of these samples. Electric dichroism was also measured for an aqueous dispersion containing sample A and a cationic molecule, [Ru(phen)(3)](2+). From the reduced linear dichroism in the visible region, an [Ru(phen)(3)](2+) ion was concluded to be adsorbed with its 3-fold symmetry axis nearly perpendicular to a surface.
  • WAKABAYASHI NOBORU, NISHIMURA SHINICHIRO, KAKEGAWA NORISHIGE, SATO HISAKO, YAMAGISHI AKIHIKO
    Clay science 日本粘土学会 12 (4) 259 - 266 0009-8574 2004/06 
    The adsorption of a cationic metal complex, [Ru(phen)_3]^<2+> (phen=1, 10-phenanthroline), onto a mica surface from its aqueous solution was investigated. An attention was focused on the effect of molecular chirality on adsorption behavior. The saturated adsorption was determined to be (1.7±0.1)×10^<-6> and (1.3±0.1)×10^<-6> mol g^<-1> for the racemic mixture and the △- or Λ-enantiomer, respectively. When adsorption was made from a partially resolved solution of [Ru(phen)_3](ClO_4)_2, the increase of enantiomeric excess was observed in a supernatant with the progress of adsorption. The results indicated that [Ru(phen)_3]^<2+> was adsorbed as a racemic pair rather than as an enantiomeric pair. Atomic force microscope observation showed that the surface remained smooth when a mica surface was in contact with an aqueous solution of racemic [Ru(phen)_3](ClO_4)_2, while it changed from a smooth surface to rough one for the △-enantiomeric solution. The change was interpreted in terms of the formation of the compact bimolecular layer for the racemic mixture, while a rough multilayer adsorption layer was formed for the enantiomer.
  • K Tamura, H Sato, S Yamashita, A Yamagishi, H Yamada
    JOURNAL OF PHYSICAL CHEMISTRY B 108 (24) 8287 - 8293 1520-6106 2004/06 Scientific journal 
    The following six types of Ru(II) complexes were synthesized with an aim to develop a monolayer with chiral discrimination: I [Ru(bpy)(2)(4-C11bpy)](ClO(4))(2) (bpy = 2,2'-bipyridine, 4-C11bpy = 4-methyl-4'-undecyl-2,2'-bipyridine); 2 [Ru(bpy)2(4,4'-dC11bpy)](ClO(4))2 (4,4'-dC11bpy = 4,4'-diundecyl-2,2' -bipyridine); 3 k[Ru(bpy)(2)(5-C11bpy)](ClO(4))(2) (5-C11bpy= 5-methyl-5'-undecyl-2,2'-bipyridine); 4 [Ru(bpy)2(5,5'-dC11py)](ClO(4))(2) (5,5'-dC11bpy = 5,5'-diundecyl-2,2'-bipyridine); 5 [Ru(bpy)2(4-C18bpy)](ClO(4))(2) (4-C18bpy= 4-methyl-4'-octadecyl-2,2'-bipyridine); 6 [Ru(bpy)2(4,4'-dC18bpy)] (ClO(4))(2) (4,4'-dC11bpy = 4,4'-dioctadecyl-2,2'-bipyridine). These complexes possess one or two alkyl chains at 4,4'- or 5,5'-positions of the 2,2'-bipyridine ligand. A traditional amphiphile is a linear molecule with a polar head attached by one or two alkyl chains, whereas the present complexes cover both traditional (1, 2, 5, and 6) and nontraditional amphiphilic molecules (3 and 4). The monolayer behavior of these Ru(II) complexes on a subphase of 0.1 M NaClO(4) aqueous solution was compared using surface pressure-molecular area (pi-A) isotherm measurements and Brewster angle microscopy (BAM) observations. The vertical structure of monolayers deposited onto a silicon substrate was characterized with X-ray reflectivity (XRR) measurements. Chirality effects were investigated using two procedures: one was to compare the pi-A isotherms between a racemic mixture and a pure enantiomer and the other to observe the effect of chiral anions in the subphase. As a result, complex 4 ([Ru(bpy)2(5,5'dC11bpy)](ClO(4))(2)), belonging to the nontraditional group, was the only molecule with a distinct chirality discrimination capability toward the chiral anion, bis[(+)-tartrato][diantimonato(Ill)]dipotassium, K(2)[Sb(2)(+)(C(4)H(2)O(6))(2)]. The observed chiral distinction of this molecule was interpreted in terms of a preferential orientation of the polar head with respect to the aqueous phase.
  • Junxiang He, Peijie Yang, Hisako Sato, Yasushi Umemura, Akihiko Yamagishi
    Journal of Electroanalytical Chemistry 566 (1) 227 - 233 1572-6657 2004/05 [Peer-reviewed]
     Scientific journal 
    We performed the photodeposition of Ag clusters onto a TiO2 nanosheet hybridized with an amphiphlic Ru(II) complex (denoted by TiO 2-Ru/Ag). Firstly a floating monolayer of [Ru(phen) 2(dC18bpy)](ClO4)2 (phen = 1,10-phenanthroline, dC18bpy = 4,4′-dioctadecyl-2,2′-bipyridyl) was formed on an aqueous dispersion of exfoliated layered titanate, (TBAOH)xTi 2-x/4□x/4O4 · H2O (x ∼ 0.7 □, vacancy TBAOH = tetrabutylammonium hydroxide) (denoted as TiO2 nanosheet). The monolayer acted as the organic part for the hybridization of TiO2 particles in an aqueous phase. A hybrid film of TiO2 nanosheet and an amphiphilic metal complex (denoted by TiO 2-Ru) was transferred onto an indium tin oxide substrate by the vertical dipping method. Thereafter the electrode was immersed in 1.0 M AgNO3 for 10 min and rinsed with water. The electrode was irradiated for 30 min by a Xe-lamp (150 W). Atomic force microscope, X-ray photoelectron spectra and cyclic voltammometry showed the formation of silver nanoparticles with a radius of 20-150 nm. The photocurrent response was measured in the potential range of 0.2-1.2 V (vs. Ag|AgCl|KCl(sat)) under the illumination of light (> 350 nm). The current increased 1.7 times when the layer number of hybrid films increased from one to two. It should be emphasized that such an increase of photocurrent with a layer number was not observed in the absence of Ag particles. © 2003 Elsevier B.V. All rights reserved.
  • JX He, PJ Yang, H Sato, Y Umemura, A Yamagishi
    JOURNAL OF ELECTROANALYTICAL CHEMISTRY 566 (1) 227 - 233 0022-0728 2004/05 Scientific journal 
    We performed the photodeposition of Ag clusters onto a TiO2 nanosheet hybridized with an amphiphlic Ru(II) complex (denoted by TiO2-Ru/Ag). Firstly a floating monolayer of [Ru(phen)(2)(dC18bPY)](ClO4)(2) (phen = 1,10-phenanthroline, dC18bpy = 4,4'-dioctadecyl-2,2'-bipyridyl) was formed on an aqueous dispersion of exfoliated layered titanate, (TBAOH)(x) Ti(2-x/4)square(x/4)O(4).H2O (x similar to 0.7: square, vacancy; TBAOH = tetrabutylammonium hydroxide) (denoted as TiO2 nanosheet). The monolayer acted as the organic part for the hybridization of TiO2 particles in an aqueous phase. A hybrid film of TiO2 nanosheet and an amphiphilic metal complex (denoted by TiO2-Ru) was transferred onto an indium tin oxide substrate by the vertical dipping method. Thereafter the electrode was immersed in 1.0 M AgNO3 for 10 min and rinsed with water. The electrode was irradiated for 30 mill by a Xe-lamp (150 W). Atomic force microscope, X-ray photoelectron spectra and cyclic voltammometry showed the formation of silver nanoparticles with a radius of 20-150 nm. The photocurrent response was measured in the potential range of 0.2-1.2 V (vs. Ag\AgCl\KCl(sat)) under the illumination of light (>350 nm). The current increased 1.7 times when the layer number of hybrid films increased from one to two. It should be emphasized that such an increase of photocurrent with a layer number was not observed in the absence of Ag particles. (C) 2003 Elsevier B.V. All rights reserved.
  • WAKABAYASHI NOBORU, NISHIMURA SHIN-ICHIRO, KAKEGAWA NORISHIGE, SATO HISAKO, YAMAGISI AKIHIKO
    Clay Sci. The Clay Science Society of Japan 12 (4) 259 - 266 0009-8574 2004 
    The adsorption of a cationic metal complex, [Ru (phen) <SUB>3</SUB>] <SUP>2+</SUP> (phen=1, 10-phenanthroline), onto a mica surface from its aqueous solution was investigated. An attention was focused on the effect of molecular chirality on adsorption behavior. The saturated adsorption was determined to be (1.7±0.1)×10<SUP>-6</SUP> and (1.3±0.1)×10<SUP>-6</SUP> mol g<SUP>-1</SUP> for the racemic mixture and the Δ-or Δ-enantiomer, respectively. When adsorption was made from a partially resolved solution of [Ru (phen) <SUB>3</SUB>](ClO<SUB>4</SUB>) <SUB>2</SUB>, the increase of enantiomeric excess was observed in a supernatant with the progress of adsorption. The results indicated that [Ru (phen) <SUB>3</SUB>] <SUP>2+</SUP> was adsorbed as a racemic pair rather than as an enantiomeric pair. Atomic force microscope observation showed that the surface remained smooth when a mica surface was in contact with an aqueous solution of racemic [Ru (phen) <SUB>3</SUB>](ClO<SUB>4</SUB>) <SUB>2</SUB>, while it changed from a smooth surface to rough one for the Δ-enantiomeric solution. The change was interpreted in terms of the formation of the compact bimolecular layer for the racemic mixture, while a rough multilayer adsorption layer was formed for the enantiomer.
  • Junxiang He, Hisako Sato, Peijie Yang, Akihiko Yamagishi
    Journal of Electroanalytical Chemistry 560 (2) 169 - 174 1572-6657 2003/12 [Peer-reviewed]
     Scientific journal 
    An ITO electrode modified with a hybrid film of chiral metal complex (Λ-[Os(phen)3]2+) and a clay (montmorillonite) has been prepared for the purpose of chiral sensing. As a first step, a floating monolayer of amphiphilic Os(II) complex, [Os(phen) 2(dC18bpy)](ClO4)2 (phen = 1,10-phenanthroline, dC18bpy = 4,4′-dioctadecyl-2,2′-bipyridyl), was formed on an aqueous dispersion of sodium montmorillonite. The monolayer acted as an organic part for the hybridization of clay particles in an aqueous phase. The hybrid film of clay and amphiphilic metal complex was transferred onto an indium tin oxide (ITO) substrate by the vertical dipping method. The next step was to immerse the electrode in chloroform, during which the amphiphilic Os(II) complex was removed from the clay surface. Thereafter the electrode was immersed in an aqueous solution of 0.5 mM Λ-[Os(phen) 3](ClO4)2 and rinsed with water. Cyclic voltammetric measurements were performed at each step of the above procedures. When the observed curves were simulated on the basis of a double-layered modified electrode, the electron transfer rate constant (k1) for Λ-[Os(phen)3]2+/Λ-[Os(phen) 3]3+ was determined to be 0.25 s-1. This OsII/OsIII redox couple was found to mediate the electrochemical oxidation of chiral 1,1′-2-binaphthol in a stereoselective way: i.e., the S-isomer was oxidized at a 1.4 times higher rate than the R-isomer. © 2003 Elsevier B.V. All rights reserved.
  • JX He, H Sato, PJ Yang, A Yamagishi
    JOURNAL OF ELECTROANALYTICAL CHEMISTRY 560 (2) 169 - 174 0022-0728 2003/12 Scientific journal 
    An ITO electrode modified with a hybrid film of chiral metal complex (Lambda-[Os(phen)(3)](2+)) and a clay (montmorillonite) has been prepared for the purpose of chiral sensing. As a first step, a floating monolayer of amphiphilic Os(II) complex, [Os(phen)(2)(dC18bpy)](ClO4)(2) (phen = 1,10-phenanthroline, dC18bpy = 4,4'-dioctadecyl-2,2'-bipyridyl), was formed on an aqueous dispersion of sodium montmorillonite. The monolayer acted as an organic part for the hybridization of clay particles in an aqueous phase. The hybrid film of clay and amphiphilic metal complex was transferred onto an indium tin oxide (ITO) substrate by the vertical dipping method. The next step was to immerse the electrode in chloroform, during which the amphiphilic Os(II) complex was removed from the clay surface. Thereafter the electrode was immersed in an aqueous solution of 0.5 mM Lambda-[Os(phen)(3)](ClO4)(2) and rinsed with water. Cyclic voltammetric measurements were performed at each step of the above procedures. When the observed curves were simulated on the basis of a double-layered modified electrode, the electron transfer rate constant (k(1)) for Lambda-[Os(phen)(3)](2+)/Lambda-[Os(phen)(3)](3+) was determined to be 0.25 s(-1). This Os-II/Os-III redox couple was found to mediate the electrochemical oxidation of chiral 1,1'-2-binaphthol in a stereoselective way: i.e., the S-isomer was oxidized at a 1.4 times higher rate than the R-isomer. (C) 2003 Elsevier B.V. All rights reserved.
  • H Sato, K Ono, T Sasaki, A Yamagishi
    JOURNAL OF PHYSICAL CHEMISTRY B 107 (36) 9824 - 9828 1520-6106 2003/09 Scientific journal 
    Stacked and single-layered lepidocrocite-type titanium dioxides (hereafter denoted as single-layered and stacked TiO2's, respectively) have been investigated by using first-principles calculations within density functional theory. The crystal structures, electronic structures, dielectric properties, and mechanical properties have been studied. The validity of the present theory was confirmed by reproducing the experimental properties of known bulk TiO2 polymorphs (rutile and anatase). As for a single-layered lepidocrocite-type TiO2, the optimized structural parameters agree well with the reported data of an exfoliated nanosheet of Ti0.91O2 or Cs(0.7)Ti(1.825)O(4)rectangle(0.175) (rectangle = vacancy). Single-layered TiO2 is slightly less stable than rutile and anatase. The band gap of single-layered TiO2 is 3.15 eV, which is larger than those of rutile and anatase due to a quantum size effect in a two-dimensional structure with a thickness less than 1 nm. The dielectric constant of the single-layered lepidocrocite-type TiO2 is highly anisotropic. The elastic constant of single-layered TiO2 shows an extra flexibility along the sheet normal.
  • H Sato, A Morita, K Ono, H Nakano, N Wakabayashi, A Yamagishi
    LANGMUIR 19 (17) 7120 - 7126 0743-7463 2003/08 Scientific journal 
    This work aims at understanding the formation and stability of a layered structure of brucite mineral [Mg(OH)(2)] via density functional calculations. Because Mg-O-Mg bond formation from a hydrolyzed species of Mg(II) ion is a critical elemental step of mineralization, we studied the reaction mechanism of Mg-O-Mg linkage using a model cluster, [Mg(OH)(2)](n) (n = 1-10), in the gas phase and a water solution. The results indicate that no barrier exists during the reaction path from [Mg(OH)(2)](n-1) + Mg(OH)(2) to [Mg(OH)(2)](n) with no significant solvent effect of water. It has been confirmed that this polymerization reaction leads spontaneously to a planar cluster, which is regarded as a part of the brucite layer. The results suggest that the layered structure of brucite is a natural consequence of polymerization. These findings will be utilized to establish microscopic modeling for studying a templating effect on the formation of an inorganic thin film.
  • K Naka, H Sato, T Fujita, N Iyi, A Yamagishi
    JOURNAL OF PHYSICAL CHEMISTRY B 107 (33) 8469 - 8473 1520-6106 2003/08 Scientific journal 
    Two kinds of metal complexes, an achiral metal complex, [Fe(terpy)](2+) (terpy = 2,2',2"-terpyridyl), and a chiral metal complex, Delta-[Ni(phen)(3)](2+) (phen = 1,10-phenanthroline), were coadsorbed by colloidally dispersed sodium saponite clay. Interaction between these molecules on a clay surface was investigated by electric dichroism and circular dichroism measurements. The molecular orientation of an adsorbed [Fe(terpy)](2+) ion was determined in the absence or presence of Delta-[Ni(phen)(3)](2+) by electric dichroism measurements. The angle of the C-2 axis of [Fe(terpy)](2+) with respect to a clay surface changed from 35.4degrees to 44.4degrees when the complex was coadsorbed with Delta-[Ni(phen)3](2+). The circular dichroism spectrum of a clay dispersion containing [Fe(terpy)]Cl-2 and Delta-[Ni(phen)(3)]Cl-2 was measured in the wavelength region of 350-600 nm. Delta-[Ni(phen)(3)](2+) had no electronic absorption in this region. Circular dichroism due to adsorbed [Fe(terpy)](2+) appeared when Delta-[Ni(phen)(3)]Cl-2 was added to the ratio of [Fe(terpy)]Cl-2/Delta-[Ni(phen)(3)]Cl-2 from 1:1 to 1:3. The results were compared with the prediction by Kirkwood-Tinoco theory, in which circular dichroism is assumed to be induced by dipolar interaction with a chiral molecule.
  • H Sato, M Ohtsuka, K Makabe, Y Kondo, K Yanagisawa, PM Lee
    IEICE TRANSACTIONS ON ELECTRONICS E86C (5) 842 - 849 0916-8524 2003/05 Scientific journal 
    This paper presents an efficient application of hot-carrier reliability simulation to delay libraries of 0.18 mum and 0.14 mum gate length logic products. Using analysis of simple primitive inverter cells, a design rule was developed in restricting signal rise time, and delay libraries of actual products were screened to check whether the rise time restrictions were met. At 200 MHz. maximum rise time (0-100%) triseMAX was 0.8 nsec (17% of duty) under Deltatd/td = 5%. For a 800,000 net product, only 25 simulations were done (each less than one minute CPU time) for the internal devices with screening done for this logic process. 30 nets were caught, but judged reliable due to their reduced duty.
  • H Sato, M Ohtsuka, K Makabe, Y Kondo, K Yanagisawa, PM Lee
    IEICE TRANSACTIONS ON ELECTRONICS E86C (5) 842 - 849 0916-8524 2003/05 Scientific journal 
    This paper presents an efficient application of hot-carrier reliability simulation to delay libraries of 0.18 mum and 0.14 mum gate length logic products. Using analysis of simple primitive inverter cells, a design rule was developed in restricting signal rise time, and delay libraries of actual products were screened to check whether the rise time restrictions were met. At 200 MHz. maximum rise time (0-100%) triseMAX was 0.8 nsec (17% of duty) under Deltatd/td = 5%. For a 800,000 net product, only 25 simulations were done (each less than one minute CPU time) for the internal devices with screening done for this logic process. 30 nets were caught, but judged reliable due to their reduced duty.
  • JX He, H Sato, P Yang, A Yamagishi
    ELECTROCHEMISTRY COMMUNICATIONS 5 (5) 388 - 391 1388-2481 2003/05 Scientific journal 
    A stereoselective solid surface has been created by the self-assembly of a chiral osmium complex, lambda-[Os(phen)(3)](ClO4)(2) (phen = 1,10-phenanthroline), onto a single layered clay film deposited on an indium tin oxide (ITO) electrode; the Os-II-Os-III redox couple mediates the electrochemical oxidation of chiral 1,1'-2-binaphthol in a stereoselective way or the S-isomer is oxidized at 1.4 times higher rate than the R-isomer. (C) 2003 Elsevier Science B.V. All rights reserved.
  • H Sato, A Yamagishi, K Kawamura
    JOURNAL OF PHYSICAL CHEMISTRY B 105 (33) 7990 - 7997 1089-5647 2001/08 Scientific journal 
    Molecular dynamics (MD) simulations have been performed to study the flexibility of smectite clay minerals. We aim at the quantitative understanding of the mechanical behavior of a single clay layer in a completely exfoliated state. The repeating unit of a clay layer is taken to be a(0) = 0.52 nm and b(0) = 0.902 nm with formula of 2Na(1/3) Al-2[Si11/3Al1/3]O-10(OH)(2) which corresponds to that of beidellite. When the size of the basic cell (A = 9.3 nm, B = 2.6 nm, and C = 5 nm) (denoted by A-type cell) is reduced by 3-40% in the A-direction, the stationary structure of a clay layer is obtained as a curved sheet with a 2:1 smectite-type layer structure. In such a curved state, the layer experiences a stress of 0.5-0.7 GPa. The layer structure of a clay fractures when the size of the same basic cell is reduced by more than 40%. The bending constant is estimated for a curved layer by plotting the inverse of the average radius against stress. The similar calculations are performed by reducing the size of the basic cell (A = 3.1 nm, B = 10.7 nm, and C = 5 nm) (denoted by B-type cell) in the B-direction. The clay layer is found to be more flexible along the A-axis direction than along the B-axis direction. When the microscopic structure of a curved clay layer is examined, it is concluded that the main origin of flexibility lies in the change of Si-O-Si angles in the silicate tetrahedral sheets rather than in the change of bond lengths.
  • H Sato, M Ohtsuka, K Yanagisawa, PM Lee
    PROCEEDINGS OF THE IEEE 2001 CUSTOM INTEGRATED CIRCUITS CONFERENCE 267 - 270 2001 [Peer-reviewed]
     International conference proceedings 
    This paper presents an efficient application of hot-carrier reliability simulation to 0.18 mum and 0.14 mum gate length logic products. Using analysis of simple primitive inverter cells, a design rule was developed in restricting signal rise time, and delay libraries of actual products were screened to check whether the rise time restrictions were met. At 200MHz, maximum rise time (0-100%) triseMAX was 0.8nsec (17% of duty) under Delta td/td = 5%. For a 800,000 net product, only 25 simulations were done teach less than one minute CPU time) for the internal devices with screening done for this logic process. 30 nets were caught, but judged reliable due to their reduced duty.
  • PM Lee, H Sato
    SOLID-STATE AND INTEGRATED-CIRCUIT TECHNOLOGY, VOLS 1 AND 2, PROCEEDINGS 1112 - 1117 2001 [Peer-reviewed]
     International conference proceedings 
    We have applied hot-carrier circuit-level reliability simulation to memory and ASIC logic products. We used two different approaches: for memory products we applied circuit-level simulation to entire circuits to over 12k transistors so that areas with worst degradation are not missed due to simulating only certain circuit blocks. We present applications to DRAM and SRAM products, and a design curve to directly relate device-level degradation to circuit degradation. For 0.18um and 0.14um logic products, we analyzed simple inverters to create design guidelines for maximum transition time to screen delay library cells to insure adequate reliability. At 200MHz, maximum transition time (0-100%) was 0.8nsec (17% of duty) for speed degradation = 5% after 10-year operating lifetime. Analyzing an 800,000 net product required only a couple hours. We screened out 30 nets. which were later judged reliable due to their reduced signal duty.
  • T. Fukuda, A. Honzawa, S. Wada, K. Mori, H. Kunitomo, H. Sato
    International Workshop on Statistical Metrology, Proceedings, IWSM 54 - 57 2001/01 
    We designed a 0.12-μm CMOS device using TCAD statistical simulation. We investigated techniques to reduce subthreshold leakage currents (Ioff) without degrading device performance to make IDDQ tests effective for large-scale and high-performance MPUs. Roll-off characteristics of threshold voltages were optimized with considering process variations and maximum loft limitations. We demonstrated that a device with relatively large roll-off characteristics is superior to a conventional one in terms of MPU operation frequency.
  • H Sato, Y Ito, H Kunitomo, H Baba, S Isomura, H Masuda
    IEICE TRANSACTIONS ON ELECTRONICS E83C (8) 1295 - 1302 0916-8524 2000/08 Scientific journal 
    In MPU and ASIC design with 0.2 mu m BICMOS LSIs, it is well known that interconnect delay becomes one of the key data to ensure high operating frequency. To verify the whole path delay accurately, one needs to create huge delay and waveform libraries which reflect updated process and interconnect structure as well as device performance. Because of the necessity for more than 100k times of circuit simulation to create the libraries, it was impossible to update the library quickly including process variation effects. In this paper, we have proposed a realistic new method to generate the libraries on the basis of RSM (Response Surface Method). In application for a BiCMOS ASIC process, we have verified that the new method has achieved the reduction of library creation time to 1/100 within the delay error of 3%. This technique can be used in our TCAD and DA framework, which gives a predictive TCAD generation of delay libraries in concurrent ASIC system and process development.
  • Hisaaki Kunitomo, Hisako Sato, Katsumi Tsuneno, Ryuichi Ikematsu, Hiroo Masuda
    International Workshop on Statistical Metrology, Proceedings, IWSM 38 - 41 1999/12 
    An industrial statistical worst case modeling for 0.2μm CMOS is presented. It is based on new TCAD-prototyping with efficient correlation analysis for CMOS performance goals under process variability. Since the manufacturing process undergoes ongoing improvement, well-calibrated TCAD is primary tool to construct realistic performance corner models. Robust TCAD calibration method is one of the key to achieve the accurate prediction. Statistically least conservative 'Worst case' conditions are newly identified, which states 99.7% of device performance is contained between the FF (Fast Fast) and SS (Slow Slow) worst corners. This reduces design guardband by 10%, compared with conventional Worst case approaches.
  • N. Natsuaki, A. Shima, M. Honda, S. Nagayama, H. Sato, T. Hashimoto
    Proceedings of the International Conference on Ion Implantation Technology 1 474 - 477 1999/12 
    Impact of the surface treatment on the redistribution of low energy implanted boron atoms is investigated for the deep sub-micron ULSI processing. It is of importance to control the ambient and temperature, in respect to encapsulation, during annealing, as well as screen oxide thickness and post-implant cleaning for dose retention and profile tailoring. An optimization of these factors is demonstrated for BF2 + implantation to form a shallow bipolar transistor base.
  • Hisako Sato, Yuko Ito, Hisaaki Kunitomo, Hiroyuki Baba, Satoru Isomura, Hiroo Masuda
    International Conference on Simulation of Semiconductor Processes and Devices, SISPAD 95 - 98 1999/12 
    In MPU/ASIC design with 0.2 μm BiCMOS LSIs, it is well known that interconnect delay becomes one of the key data to ensure high operating frequency. To verify the whole path delay accurately, one needs to create huge delay and waveform libraries which reflect updated process and interconnect structure as well as device performance. Because of the necessity for more than 100 k times of CKT simulation to create the libraries, it was impossible to update the library quickly including process variation effects. In this paper, we have proposed a realistic new method to generate the libraries, 100 times faster without loosing accuracy. In application for a BiCMOS ASIC process, we have verified that the new method has achieved a reduced library creation-time of 1/100 within the delay error of 3%. This technique can be used in our TCAD/DA framework, which gives a predictive TCAD generation of delay-libraries in concurrent ASIC system and process development.
  • Hisako Sato, Yasunobu Yanagisawa
    Journal of the Electrochemical Society 146 (1) 367 - 371 0013-4651 1999 Scientific journal 
    Precise phosphorus profiles were obtained in the region of an Si/SiO2 interface by means of inductively coupled plasma mass spectrometry (ICPMS), secondary ion mass spectroscopy (SIMS), and spreading resistance profiling (SRP) measurements. Samples were prepared by implanting phosphorous at low dose, annealing, and oxidizing by wet oxidation. According to ICP-MS, the total amounts of phosphorus were extremely low in the SiO2 side. The same results held when the oxidation temperature was changed from 800 to 900°C. SIMS measurement in conjunction with ICP mass measurement showed that the pileup of phosphorus occurred in the silicon side at the Si/SiO2 interface. SRP confirmed that the pileup of phosphorus was electrically inactive. As a result, the active amount of phosphorus in the Si side was reduced to about 60%. The simulation based on the monolayer formation at the the SiO2/Si interface was proposed to describe the observed pileup phenomenon of phosphorus. © 1999 The Electrochemical Society. 50013-4651(98)03-117-6. All rights reserved.
  • Hisako Sato, Masami Ikota, Aritoshi Sugimoto, Hiroo Masuda
    IEEE Transactions on Semiconductor Manufacturing 12 (4) 409 - 418 0894-6507 1999 Scientific journal 
    We have proposed a novel discrete exponential distribution function, which describes a defect count distribution on wafers or chips more accurately, especially in near defect-free conditions. The conventional approach based on a gamma probability density function (g-pdf) isknown to fail in expressing the defects of defect-free wafers or chips, because it always gives zero as the pdf value. Since the number of defects is countable (discrete distribution should be used) and analyzed in terms of nondefective chip yield, the g-pdf cannot be used because of its inaccuracy in the near defect-free condition. A discrete exponential pdf is introduced cor responding to the defect count distribution. In addition, a convolution formula of the new pdf is derived statistically which can express realistic defect count distribution with multiple defect sources. It is noted that the popular negative binomial yield formula (NBYF) is directly derived with the convoluted discrete exponential distribution, which inter prets the cluster factor given in NBYF as the number of different defect sources predicted. It is experimentally proven that defect count distributions are approximated by this new model within an average error of about 0.01 defects per wafer from film deposition process data.
  • Hisako Sato, Masami Ikota, Aritoshi Sugimoto, Hiroo Masuda
    International Workshop on Statistical Metrology, Proceedings, IWSM 28 - 31 1998/12 
    We have proposed a novel discrete exponential distribution function, which describes defect-counts distribution on wafers and/or chips more accurately, especially for close to defect-free condition. Conventional approach based on a gamma probability density function (g-pdf) is known to fail in expressing the defect-free wafers or chips, which gives always 0 pdf value. Since the number of faulty-defect should be countable (discrete) and analyzed in terms of non-defect chip yield, the g-pdf cannot be used because of its inaccuracy in near defect-free condition. A new discrete formula which is built by the idea of discrete exponential pdf has been developed. It well describes the situation of the defect-counts distribution of near defect-free wafers. It is experimentally proved that defect-counts distributions are approximated with the new model within an average error of about 0.01 defects/wafer in a film deposition process data.
  • H Sato, H Kunitomo, K Tsuneno, K Mori, H Masuda
    IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING 11 (4) 575 - 582 0894-6507 1998/11 Scientific journal 
    Effects of statistical process variation on the 0.35-mu m CMOS performance have been accurately characterized by using a new calibrated TCAD methodology. To conduct the variation analysis, a series of TCAD simulations was conducted on the basis of DoE (design of experiments) with optimum variable transformations, which resulted in RSF's (response surface functions) for threshold voltage (V-th) and saturation drain current (I-ds) A new global calibration of the RSF model based on experimental data gives excellent accuracy within 0.02 V error in V-th and 3% error in Ida Using calibrated RSF, statistical process variation effects on the device characteristics have been quantitatively evaluated for each process recipe. It is found that variation of the gate-oxide formation process shows the most significant effect on the NMOS Delta I-ds in the production process. Furthermore we have designed an optimized 0.25-mu m CMOS process and device on the basis of the RSF and also predicted the process variation effects on the device performance, It is shown that the V-th and I-ds variations of the 0.25-mu m CMOS exhibit less than 10% I-ds variation in the production level process, which is similar to the value of 0.35-mu m CMOS experimental data. Additional TCAD simulations for MOS model parameter generation of the 0.25-mu m device was also conducted to allow circuit-designers to use predictive worst case circuit design parameters before experimental chip fabrication.
  • H Masuda, K Tsuneno, H Sato, K Mori
    PROCEEDINGS OF THE ASP-DAC '98 - ASIA AND SOUTH PACIFIC DESIGN AUTOMATION CONFERENCE 1998 WITH EDA TECHNO FAIR '98 129 - 134 1998 [Peer-reviewed]
     International conference proceedings 
    We have proposed, in this paper a, TCAD/DA methodology for MPU and ASIC with updated processes and devises, which allow a predictive chip-design with quick quantitative correlation studies between process-recipe and CKT & delay parameters required in DA works. Effects of statistical process variation on 0.35um CMOS have been rigorously characterized with a new global TCAD calibration technique. Based on the data, process variation effects on a 0.25um CMOS have been predicted, which is concluded that the Vth and Ids total-variation of the 0.25um CMOS shows less than 10% in production process, which is similar with that of the 0.35um CMOS.
  • H Sato, K Tsuneno, H Masuda
    ICMTS 1998: PROCEEDINGS OF THE 1998 INTERNATIONAL CONFERENCE ON MICROELECTRONIC TEST STRUCTURES 193 - 196 1998 International conference proceedings 
    A novel unified TED (Transient Enhanced Diffusion) model for RTA and furnace processes is proposed on the basis of the vacancy-assisted diffusion model. The effective diffusivity is described by a RSF (Response Surface Function) based on relaxation-time approximation of point defects, which depends on the annealing temperature and implant dose. The parameters were calibrated with a set of experimental database of test structures. The ramp-up effect is taken into account with new budget equation of damage relaxation. Especially the induced damage of BF2 implant was demonstrated. It results in an excellent experimental agreement within Delta xj < 0.01 mu m for xj=0.08-0.15 mu m NIP junction formations.
  • Hisako Sato, Hisako Sato, Katsumi Tsuneno, Katsumi Tsuneno, Kimiko Aoyama, Kimiko Aoyama, Takahide Nakamura, Takahide Nakamura, Hisaaki Kunitomo, Hisaaki Kunitomo, Hiroo Masuda, Hiroo Masuda
    IEICE Transactions on Electronics E79-C 226 - 232 0916-8524 1996/12 
    A new methodology for simulation-based CMOS process design has been proposed, using a Hierarchical Response Surface Method (HRSM) and an efficient experimental calibration. The design methodology has been verified using a 0.4 micron CMOS process. The proposed HRSM achieved a 60% reduction of process and device design cost in comparison with those of conventional TCAD. The procedure was performed in conjunction with an experimental calibration technique to provide a reliable threshold voltage prediction including process variation effects. The total CPU cost was 200 hr. on SUN SPARC 10 and the error of the predicted threshold voltage was less than 0.02 V. © 1995 IEEE.
  • A Yamagishi, M Taniguchi, Y Imamura, H Sato
    APPLIED CLAY SCIENCE 11 (1) 1 - 10 0169-1317 1996/10 Scientific journal 
    1,1'-Binaphthol was resolved chromatographically on a column packed with Lambda-[Ru(phen)(3)](2+) and Lambda-[Ru(bpy)(3)](2+) laponite columns when the compound was eluted with methanol solvent. The elution order of 1,1'-binaphthol enantiomers was R --> S and S --> R for the [Ru(phen)(3)](2+) and Lambda-[Ru(bpy)(3)](2+) columns, respectively. From the temperature dependence of the retention time for each enantiomer, the difference of enthalpy of adsorption between the R- and S- enantiomers, -Delta H-R - (-Delta H-S), was obtained to be -2.7 and 5.3 kcal/mol for the Delta-[Ru(phen)(3)](2+) and Lambda-[Ru(bpy)(3)](2+) columns, respectively. The adsorption structures of 1,1'-binaphthol enantiomers were studied by the X-ray diffraction analyses of the powder samples of clay-Ru(II) complex-1,1'-binaphthol adducts. The stability of the binding of 1,1'-binaphthol was examined by the theoretical simulations based on the Monte Carlo method.
  • H Sato, A Yamagishi, K Naka, S Kato
    JOURNAL OF PHYSICAL CHEMISTRY 100 (5) 1711 - 1717 0022-3654 1996/02 Scientific journal 
    The adsorption behaviors of tris(1,10-phenanthroline)metal(II) ([M(phen)(3)](2)) by saponite clay have been simulated by the Monte Carlo method. A two-dimensional sheet of linked [SiO4](4-) and [AlO4](5-) tetrahedra is used for the model tetrahedral sheet of a saponite day. The thermal distributions of the configurations are obtained using the Metropolis algorithm at 300 K for the systems which have racemic or enantiomeric metal complex molecules intercalated between two sheets. For adsorption within the cation exchange capacity (CEC), the interlayer distance at the thermal equilibrium is obtained to be 10.5 Angstrom for both the racemic and enantiomeric chelates. For adsorption over the CEC, the interlayer distance is 18.5 and 20.7 Angstrom for the racemic and enantiomeric chelates in the presence of SO42- anions, respectively. The racemic mixture with SO42- has a mean binding energy 31.1 kJ/mol lower than that of the pure enantiomer. In both cases, the adsorbed molecules form a bimolecular layer with the anions at the middle of two sheets. These predictions are compared with the experimental observations of adsorption of [Ru(phen)(3)]SO4 by colloidally dispersed synthetic saponite.
  • H Sato, K Aoyama, K Tsuneno, H Masuda
    SISPAD '96 - 1996 INTERNATIONAL CONFERENCE ON SIMULATION OF SEMICONDUCTOR PROCESSES AND DEVICES 95 - 96 1996 [Peer-reviewed]
     International conference proceedings
  • Kimiko Aoyama, Kiyoshi Ise, Hisako Sato, Katsumi Tsuneno, Hiroo Masuda
    IEEE Transactions on Semiconductor Manufacturing 9 (1) 20 - 26 0894-6507 1996 Scientific journal 
    This paper describes the generation of a new universal design chart for submicron multilevel interconnection and its verification using test-structures. This has been developed to give the precise interconnect-capacitance for parallel submicron multilevel interconnections. Parasitic effects of a passivation film (Si3 N4) on the interconnect capacitance have been also studied. The results of the test-structures designed have shown an excellent agreement with the design-chart with a maximum error of 8%. Furthermore, a simple propagation delay and response voltage model to a step voltage input have been developed incorporating the parallel-interconnect capacitance model. The new model is based on a lossy-transmission line equation and demonstrates an excellent agreement with RC lumped circuit simulations, resulting in a new simple and accurate prediction method for interconnect delay for use in VLSI timing design. © 1996 IEEE.
  • K TSUNENO, H SATO, H MASUDA
    IEICE TRANSACTIONS ON ELECTRONICS E77C (2) 161 - 165 0916-8524 1994/02 Scientific journal 
    This paper describes modeling and simulation of submicron NMOSFET current drive focusing on carrier velocity-saturation effects. A new simple analytical model is proposed which predicts a significant degradation of drain current in sub- and quarter-micron NMOSFET's. Numerical two-dimensional simulations clarify that the degradation is namely caused by high lateral electric field along the channel, which leads to deep velocity-saturation of channel electrons even at the source end. Experimental data of NMOSFET's, with gate oxide thickness (Tox) of 9-20 nm and effective channel lengths (L(eff)) of 0.35-3.0 mum, show good agreement with the proposed model. It is found that the maximum drain current at the supply voltage of V(dd)=3.3 V is predicted to be proportional to L(eff)0.54 in submicron NMOSFET's, and this is verified with experiments.
  • H SATO, K TSUNENO, H MASUDA
    IEICE TRANSACTIONS ON ELECTRONICS E77C (2) 106 - 111 0916-8524 1994/02 Scientific journal 
    Recently, high-dose implantation and low temperature annealing have become one of the key techniques in shallow junction formation. To fabricate shallow junction in quarter-micron CMOS VLSIs, it is well known being important to evaluate the transient enhanced diffusion (TED) of implanted dopants at low temperature furnace annealing, which is caused by the damages of implantation. We have newly studied the TED phenomena by a compact empirical method. This approach has merits of simplicity and better physical intuition, because we can use only minimal parameters to describe the TED phenomena. The other purpose of this work is to evaluate two-dimensional transient enhanced diffusion focusing on phosphorus implant and furnace annealing. Firstly, we defined effective diffusivity of the TED and determined extraction procedure of the model parameters. Number of the TED model parameters is minimized to two, which describe effective enhanced diffusivity and its activation energy. The parameters have been extracted from SIMS profile data obtained from samples which range 10(13)-3 X 10(15) cm-2 and 850-950-degrees-C for phosphorus implanted dose and annealing temperature, respectively. Simulation results with the extracted transient enhanced diffusion parameters show good agreements well with the SIMS data within 2% RMS-error. Critical doses for phosphorus enhanced diffusion have been determined in 950-degrees-C annealing condition. No transient enhanced diffusion is observed at 950-degrees-C under the implant dose of 1 x 10(13) cm-2. Also the transient enhanced diffusivity is leveled off over the dose of 1 x 10(14) cm-2. It is seen that the critical dose in TED phenomena might be temperature dependent to a certain extent. We have also verified that two-dimensional effect of the TED phenomena experimentally. Two-dimensional phosphorus n- layer is chosen to verify the simulation. It was concluded that the TED has isotropic nature in phosphorus n- diffusion formation.
  • Akihiko Yamagishi, Masahiro Taniguchi, Masayuki Takahashi, Chikako Asada, Nobuyuki Matsushita, Hisako Sato
    Journal of Physical Chemistry 98 (31) 7555 - 7561 0022-3654 1994 Scientific journal 
    The adsorption of tris(5,5′-dimethyl-2,2′-bipyridyl)ruthenium(II) ([Ru(dmbpy)3]2+) by a colloidally dispersed montmorillonite or saponite is studied by electric dichroism measurements. [Ru(dmbpy)3]2+ is adsorbed up to 100% of the cation-exchange capacity (CEC). An angle (θ) between the threefold symmetry (C3) axis of a bound chelate and the direction normal to a clay surface is determined from the reduced linear dichroism extrapolated to the infinite field strength. At the loading level less than 13% of CEC, θ is determined to be 54-53° and 57-62° for montmorillonite and saponite, respectively. The results are contrasted with the bindings of [Ru(phen)3]2+ (phen = 1,10-phenanthroline) and [Ru(bpy)3]2+ (bpy = 2,2′-bipyridyl). These molecules orient the C3 axes roughly in the perpendicular direction on a clay surface (θ = 16-18°). When the amount of [Ru(dmbpy)3]2+ adsorbed is increased to 83% and 77% of CEC for montmorillonite and saponite, θ decreases to 43-46° and 50-53°, respectively. The changes are ascribed to the intermolecular interactions among the bound molecules. Notably, a definite difference is observed in the dichroism spectra whether the metal complex is adsorbed as a pure enantiomer or a racemic mixture at the higher loading level. These results are compared with the theoretical predictions based on the Monte Carlo simulations. © 1994 American Chemical Society.
  • H SATO, A YAMAGISHI, S KATO
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 114 (27) 10933 - 10940 0002-7863 1992/12 Scientific journal 
    Monte Carlo simulations are used to compare the binding states of tris(1,10-phenanthroline)metal(II) ([M(phen)3]2+) and tris(2,2'-bipyridyl)metal(II) ([M(bpy)3]2+) bound to a clay. A pair of [M(phen)3]2+ or [M(bpy)3]2+ complexes is placed on the model surface of a silicate sheet. The surface is composed of linked [SiO4]4- and [AlO4]5- tetrahedra. The binding energy is obtained as the sum of the interaction energies of the metal complexes with the sheet and the intermolecular energy between the metal complexes. The stable binding state is examined in terms of the free energy at 300 K as a function of the intermolecular distance, r(M-M). For [M(phen)3]2+, a racemic pair has the minimum free energy at r(M-M) = 9.2 angstrom, and an enantiomeric pair has the minimum free energy at r(M-M) = 13.4 angstrom. The mean binding energy (E) for the racemic pair is 1.5 kJ/mol lower than that for the enantiomeric pair. The results indicate that the racemic mixture forms a more compact and stable pair than does the pure enantiomer. For [M(bpy)3]2+, racemic and enantiomeric pairs have the minimum binding free energy at nearly the same values of r(M-M): r(M-M) = 9.3 angstrom for a racemic pair and 9.5 angstrom for an enantiomeric pair. E is 25.3 kJ/mol lower for the racemic pair than for the enantiomeric pair. Thus a pair of the metal complexes form a dimer with similar compactness irrespective of the chirality of the complexes. These results are compared with experimental observations of the chirality effects on the adsorption behaviors of these metal complexes by a clay.
  • Akihiko Yamagishi, Hiroshi Makino, Yuji Nakamura, Hisako Sato
    Clays and Clay Minerals 40 (3) 359 - 361 1552-8367 1992
  • Hisako Sato, Akihiko Yamagishi, Shigeki Kato
    Journal of Physical Chemistry 96 (23) 9377 - 9382 0022-3654 1992 Scientific journal 
    Monte Carlo simulations are used to investigate the intercalation structures of a metal complex within a smectite clay. The investigated model system is [M(phen)3]2+ (phen = 1,10-phenanthroline) intercalated between two linked [SiO4]4- and [AlO4]5- tetrahedra sheets. The free energy of binding, the roles of the upper and lower sheets in determining the orientation of a bound chelate, and the effects of water medium on the binding free energy are investigated. For interlayer distances from 10 to 18 Å, the chelate is bound by the sheets with the 3-fold (C3) symmetry axis perpendicular to the sheet surface. The chelate rotates around the C3 axis by 15-60° from the equilibrium position. A comparison with experimental data shows that agreement with Monte Carlo simulations is satisfactory, although the theoretical treatments predict more details about the bound structures of the chelate than the experimental results. © 1992 American Chemical Society.
  • Hisako Sato, Akihiko Yamagishi, Shigeki Kato
    Journal of Physical Chemistry 96 (23) 9382 - 9387 0022-3654 1992 Scientific journal 
    The adsorption of tris(1,10-phenanthroline)metal(II) ([M(phen)3]2+) by a clay is studied with Monte Carlo simulations. A two-dimensional sheet of linked [SiO4]4- and [AlO4]5- tetrahedra is used for the model tetrahedral sheet of a clay. The thermal distributions of the configurations are obtained using a Metropolis algorithm at 300 K. The binding states are compared when the racemic or enantiomeric pairs of the chelates are intercalated between two sheets separated at 11 Å. The intermolecular distance rM,M, at the minimum free energy is smaller for the racemic pair (9.2 Å) than for the enantiomeric pair (11.4Å). The racemic pair has a mean binding energy 0.0114 au (29.9 kJ/mol) lower than the enantiomeric pair. It is, therefore, concluded that the racemic pair of [M(phen)3]2+ forms a more compact and stable pair than does the enantiomeric pair. The conclusions support the recent experimental findings as to the racemic adsorption of [M(phen)3]2+ (M = Ni, Fe, and Ru) by montmorillonite. © 1992 American Chemical Society.
  • SATO HISAKO
    Clay Sci. The Clay Science Society of Japan 8 (3) 117 - 127 0009-8574 1991 
    The interaction between the talc layers is studied for a model system of two tetrahedral sheets. The upper sheet is a unit cell of tetrahedral sheet, [Si<SUB>4</SUB>0<SUB>10</SUB>] <SUP>4-</SUP> and the lower sheet an infinite hexagonal network of [Sio<SUB>4</SUB>] <SUP>4-</SUP>. Using the electrostatic and Lennard-Jones equations, the energy for the interlayer interaction is calculated under the periodic boundary conditions. It is concluded that the interaction between the above two silicate sheets is attractive. The most stable configuration is predicted to be that the Si atom in the upper sheet is located nearly in the middle of the hexagonal hole in the lower sheet.
  • SATO HISAKO, YAMAGISHI AKIHIKO, KATO SHIGEKI
    Clay Sci. The Clay Science Society of Japan 8 (3) 147 - 168 0009-8574 1991 
    Ab initio Hartree-Fock molecular orbital (MO) calculations are carried out for a system of linked [SiO<SUB>4</SUB>] <SUP>4-</SUP> and [Al0<SUB>4</SUB>] <SUP>5-</SUP>tetrahedra (denoted by a cluster). The system is regarded as a model of the tetrahedral sheet of a clay. The effective charges from the Mulliken population analyses are almost constant when the number of tetrahedra in a cluster increases from 1 to 6. The MO calculation is extended for the system of a point positive charge located over the surface of a cluster. The obtained potential curves of the point positive charge coincide well with the electrostatic potentials due to the effective charges on the atoms of the cluster. The binding energy of a metal complex ion, [M (phen) <SUB>3</SUB>] <SUP>2+</SUP> (phen=1, 10-phenanthroline), with a cluster, {[SiO<SUB>4</SUB>] <SUP>4-</SUP>} <SUB>971</SUB>/{[Al0<SUB>4</SUB>] <SUP>5-</SUP>}, is estimated in terms of the electrostatic and van der Waals energies for the atomic pairs. The orientation of the chelate at the minimum energy is compared with the recent experimental results for an adduct of the chelate with montmorillonite clay.

Books etc

  • 錯体化学辞典
    (Contributor)
    2019
  • Chapter 6 From transition metal ion complexes to chiral clay minerals
    Hisako Sato, Akihiko Yamagishi (Contributor, Chap 6)
    Elsevier 2018/11
  • Inorganic Nanosheets and Related Materilas: Fumdamentals and Applications of Two-Dimensional Systems
    Hisako Sato, Akihiko Yamagishi (Chirality and its application)
    Springer 2017 9784431564942
  • 低分子ゲルの開発と応用
    佐藤久子, 矢島知子 (Contributor, 振動円二色性分光法によるゲル形成過程の解析)
    シーエムシー出版 2016/05
  • Clay MInerals in Nature
    佐藤久子 (Contributor)
    2012
  • 日本粘土学会 (Contributor)
    技報堂出版 2009 9784765500340
  • 黒田 一幸, 佐々木 高義 (Contributor)
    シーエムシー出版 2005 4882314975
  • 化学ってそういうこと
    佐藤久子 (Contributor)
    化学同人 2003

Conference Activities & Talks

  • Real-Time Sensing of Oxygen Molecules by Ultrathin Hybrid Films of Luminescent Iridium(III) Complexes and Clay Nanosheets
    Kazuyoshi Takimoto, Akihiko Yamagishi, Hisako Sato
    日本化学会第100春季年会  2020/03
  • Application of Solid-State Vibrational Circular Dichroism for Layered Double Hydroxides: Intercalation Structure of Phenylalanine
    Hisako Sato, Kazuyoshi Takimoto, Izuru Kawamura, Sumio Aisawa
    日本化学会第100春季年会  2020/03
  • Application of Solid-state Vibrational Circular Dichroism Spectroscopy to Intercalation Compounds of Clay Minerals: Recognition of Molecular Chirality within an Interlayer Space
    Akihiko Yamagishi, Kenji Tamura, Kazuyoshi Takimoto, Hisako Sato
    ACS Pubication Symposium Inovation in materials science &tecnology  2019/11
  • NMR Chiral Sensing Based on Zinc Complex of Salen-like Ligand with CS Symmetry
    KazuyoshiTakimoto, Shinsuke Ishihara, Jan Labuta, Katsuhiko Ariga, Jonathan Hill, Masato Sumita, Shigeki Mori, Hisako Sato
    錯体化学第69回討論会  2019/09
  • Phosphorus Color Control by Use of the hybrid Langmuir-Blodgett films of Iridium Complexes and Synthetic Saponite Deposited onto a Metal Substrate  [Not invited]
    Hisako Sato, Tatsuya Yamada, Ryotaro Ozaki
    錯体化学第69回討論会  2019/09
  • 振動円二色性分光法の無機層間化合物への適用  [Not invited]
    佐藤久子, 瀧本和誉, 森寛敏, 山岸晧彦
    第13回分子科学討論会  2019/09
  • 秦泉寺良樹, 瀧本和誉, 渡邉裕, 佐藤久子
    錯体化学会討論会講演要旨集  2019/09
  • イリジウム錯体の配位アミノ酸によるキラリティ効果:振動円二色性分光法の応用  [Not invited]
    瀧本 和誉, 渡邉 裕, 佐藤 久子
    MC2019 (モレキュラーキラリティ2019)  2019/06
  • 固体振動円二色性分光法の分子認識への応用  [Not invited]
    佐藤久子, 瀧本和誉, 山岸晧彦
    MC2019 (モレキュラーキラリティ2019)  2019/06
  • 瀧本和誉, 渡邉裕, 佐藤久子
    シンポジウム「モレキュラー・キラリティー」講演要旨集  2019/06
  • 佐藤久子, 瀧本和誉, 山岸晧彦
    シンポジウム「モレキュラー・キラリティー」講演要旨集  2019/06
  • 川村出, 川村出, 佐藤久子, 尾澤夢実, 茅野洋平, 吉田純, 内藤晶
    ホスト-ゲスト・超分子化学シンポジウム講演要旨集  2019/05
  • 合成サポナイトに吸着したイリジウム錯体の発光挙動におよぼすキラリティの影響  [Not invited]
    秦泉寺 良樹, 瀧本 和誉, 渡邉 裕, 佐藤 久子
    日本化学会第99春季年会  2019/03
  • 粘土鉱物に吸着したイリジウム(III)錯体の発光特性  [Not invited]
    瀧本 和誉, 秦泉寺 良樹, 渡邉 裕, 佐藤 久子
    日本化学会第99春季年会  2019/03
  • 振動円二色性分光法を用いた軸性キラリティをもつPd二核錯体の絶対配置の決定  [Not invited]
    登口 碧, 後藤 勇太朗, 渡邉 裕, 佐藤 久子
    日本化学会第99春季年会  2019/03
  • 酸を用いた除染法  [Invited]
    佐藤久子
    環境放射能除染学会第15回講演会  2019/01
  • Application of Vibrational Circular Dichroism to Supramolecular Chirality of Molecular Aggregates  [Invited]
    Hisako Sato
    50th RAP seminor  2018/12
  • 振動円二色性測定によるインスリン凝集体の超分子キラリティ  [Not invited]
    中西文香, 佐藤久子, 座古保
    日本化学会中国四国支部大会 愛媛  2018/11
  • 末端に非対称配位子を持つ軸不斉二核パラジウム(Ⅱ)錯体の合成とその性質  [Not invited]
    登口 碧, 後藤 勇太朗, 渡邉 裕, 佐藤 久子
    日本化学会中国四国支部大会 愛媛  2018/11
  • 振動円二色性分光法を用いた固体表面での分子不斉認識機構の研究  [Not invited]
    佐藤久子, 瀧本和誉
    日本化学会中国四国支部大会 愛媛  2018/11
  • 平面型多核パラジウム錯体における軸性キラリティの発現  [Not invited]
    後藤勇太朗, 渡邉裕, 佐藤久子
    日本化学会中国四国支部大会 愛媛  2018/11
  • 粘土鉱物に吸着したキラルイリジウム(III)錯体の発光特  [Not invited]
    瀧本和誉, 渡邉裕, 佐藤久子
    日本化学会中国四国支部大会 愛媛  2018/11
  • Controlling the self-assembly of tri-peptide with d-amino acid and probing the nano-structural difference  [Not invited]
    Hisako Sato, Akira Naito, Izuru Kawamura
    ANNIC 2018 @ Langenbeck Virchow Haus  2018/10
  • Stereochemistry-dependent nanostructure of phenylalanine-based tripeptide self-assembly  [Not invited]
    Yumi Ozawa, Hisako Sato, Nana Yamaki, Yuichiro Izato, Atsumi Miyake, Akira Naito, Izuru Kawamura
    The Asian Pacific Prion Symposium 2018 (APPS2018),  2018/10
  • An Initial Interaction Difference between Bombinin H2 and H4 on Leishmania mimetic membrane  [Not invited]
    Batsaikhan Mijiddorj, Shiho Kaneda, Hisako Sato, Yuki Kitahashi, Namsrai Javkhlantugs, Akira Naito, Kazuyoshi Ueda, Izuru Kawamura
    The 56th Annual Meeting of The Biophysical Society of Japan  2018/09
  • マイクロ波照射による汚染土壌の脱セシウム化  [Not invited]
    山岸晧彦, 田村堅志, 山下浩, 佐藤久子, 森田昌敏
    第62回粘土科学討論会  2018/09
  • 層状複水酸化物にインターカレートした酒石酸誘導体の振動円二色性スペクトル  [Not invited]
    佐藤久子, 松尾拓哉, 瀧本和誉, 田村堅志, 山岸晧彦
    第62回粘土科学討論会  2018/09
  • 層状複水酸化物中にインターカレートしたアミノ酸の振動円二色性スペクトル  [Not invited]
    瀧本和誉, 佐藤久子, 會澤純雄
    第62回粘土科学討論会  2018/09
  • 合成サポナイトとイリジウム(III)錯体のハイブリッド化による発光特性  [Not invited]
    秦泉寺良樹, 瀧本和誉, 渡邉裕, 佐藤久子
    第62回粘土科学討論会  2018/09
  • 合成サポナイトに吸着したキラルイリジウム(III)錯体の発光特性  [Not invited]
    瀧本和誉, 秦泉寺良樹, 渡邉裕, 佐藤久子
    第62回粘土科学討論会  2018/09
  • Synthesis of tetranuclear Pd(II) Complex with Axial Chirality  [Not invited]
    Yutaro Goto, Yutaka Watanabe, Hisako Sato
    ICCC2018 仙台  2018/07
  • Enhancement of Luminescence for Chiral Iridium(III) Complex by Adsorption onSynthetic Saponite  [Not invited]
    Kazuyoshi Takimoto, Yutaka Watanabe, Shigeki Mori, Ahiko Yamagishi, Hisako Sato
    ICCC2018 仙台  2018/07
  • Molecular Recognition of Chiral Metal Complexes intercalated in Montmorillonite as revealed by Vibrational Circular Dichroism  [Not invited]
    Hisako Sato
    ICCC2018 仙台  2018/07
  • 軸性キラリティを持つ四核Pd錯体の合成  [Not invited]
    後藤勇太朗, 渡邉裕, 佐藤久子
    第68回錯体化学討論会  2018/07
  • キラルイリジウム錯体の合成と発光特性  [Not invited]
    瀧本和誉, 渡邉裕, 森重樹, 佐藤久子
    第68回錯体化学討論会  2018/07
  • ミニフィールド装置を用いた汚染土壌からのセシウム除去のオンサイト実験  [Not invited]
    佐藤久子, 山下浩, 大森大輔, 田村堅志, 山岸晧彦, 森田昌敏
    第7回環境放射能除染研究発表会  2018/07
  • 汚染土壌のマイクロ波処理による脱セシウム化機構の研究  [Not invited]
    山岸晧彦, 田村堅志, 山下浩, 佐藤久子, 森田昌敏
    第7回環境放射能除染研究発表会  2018/07
  • 振動円二色性分光法VCDの超分子キラリティへの応用:Dアミノ酸含有ペプチドの構造解析  [Invited]
    佐藤久子
    横浜国大  2018/06
  • モンモリロナイト表面上での不斉認識に対する振動円二色性分光法の適用  [Not invited]
    佐藤久子, 瀧本和誉, 山岸晧彦
    第16回ホストーゲスト・超分子化学シンポジウム  2018/06
  • 陽イオン性金属錯体への振動円二色性分光法の応用  [Not invited]
    佐藤久子, 瀧本和誉, 山岸晧彦
    モレキュラーキラリティ2018)  2018/05
  • Construction and Functional Characterization of Chiral Twodimensional  [Not invited]
    SASAKI, Toshiyuki, SATO, Hisako, MIYATA, Mikiji, HISAKI
    日本化学会第98春季年会(2018)  2018/03
  • Syntheses of Multinuclear Pd(II) Complexes with Axial Chirality  [Not invited]
    GOTO, Yutaro, SATO, Hisako, WATANABE, Yutaka
    日本化学会第98春季年会(2018)  2018/03
  • 合成サポナイトに吸着したキラルイリジウム錯体の発光挙動  [Not invited]
    瀧本和誉, 渡邉裕, 山岸晧彦, 佐藤久子
    日本化学会第98春季年会(2018)  2018/03
  • ペルフルオロアルキル鎖とフェニル基を有する低分子ゲル化剤  [Not invited]
    叶野花菜子, 佐藤久子, 山岸晧彦, 矢島知子
    日本化学会第98春季年会(2018)  2018/03
  • 振動円二色性分光法による固体表面における不斉識別機構の解明  [Not invited]
    佐藤久子, 瀧本和誉, 山岸晧彦
    日本化学会第98春季年会(2018)  2018/03
  • 干渉法による発光性イリジウム錯体LB膜の発光特性の向上  [Not invited]
    山田 達也, 尾崎 良太郎, 弓達 新治, 門脇 一則, 佐藤 久子
    第2回フォトニクス研究会  2017/12
  • 繊維状粘土に取り込まれた光増感配位子を含むランタニド錯体からなる無機有機複合の安定性  [Not invited]
    海崎純男, 城谷大, 岩松雅子, 加藤由美子, 佐藤久子, 日置亜矢子, 梶原篤
    第61回粘土科学討論会  2017/09
  • 粘土鉱物へのイリジウム錯体吸着による発光キラルセンシグ  [Not invited]
    山岸晧彦, 瀧本和誉, 田村堅志, 渡邉裕, 佐藤久子
    第61回粘土科学討論会  2017/09
  • 風化バイオタトへのCsイオン吸着サイトの考察  [Not invited]
    田村堅志, 清水禎, 佐藤久子, 山下浩, 山岸晧彦, 森田昌敏
    第61回粘土科学討論会  2017/09
  • キラル分離用 HPLCHPLC カラム充填剤応用に適したヘクトイ被覆シリ粒子の合成  [Not invited]
    小栗睦基, 佐藤久子, 山岸晧彦, 岡田友彦
    第61回粘土科学討論会  2017/09
  • 汚染土壌の減容化に向けた粘カラム方式ミニフィールド装置よる実証実験  [Not invited]
    佐藤久子, 田村堅志, 山下浩, 金子芳郎, 山岸晧彦, 森田昌敏
    第61回粘土科学討論会  2017/09
  • 干渉を用いたイリジウム錯体LB膜の発光特性  [Not invited]
    山田 達也, 尾崎 良太郎, 弓達 新治, 門脇 一則, 佐藤 久子
    平成29年度 電気関係学会四国支部連合大会  2017/09
  • フェニル基を有する含フッ素化合物の合成と超分子ゲルの形成  [Not invited]
    叶野花菜子, 佐藤久子, 山岸晧彦, 矢島知子
    第66回高分子討論会  2017/09
  • 繊維状粘土に取り込まれたランタニド錯体からなる多機能性無機有機複合発光体の光安定性  [Not invited]
    海崎純男, 城谷大, 岩松雅子, 加藤由美子, 佐藤久子, 日置亜矢子, 梶原篤, 山崎鈴子
    第67回錯体化学討論会  2017/09
  • 発光性イリジウム錯体の粘土面への吸着:発光キラルセンシングへの応用  [Not invited]
    山岸晧彦, 瀧本和誉, 田村堅志, 渡邉裕, 佐藤久子
    第67回錯体化学討論会  2017/09
  • リジウム錯体のLB膜を用いた光集約系の構築  [Not invited]
    佐藤久子, 田村堅志, 山岸晧彦
    第67回錯体化学討論会  2017/09
  • 軸性キラリティを持つ多核パラジウム錯体の合成と性質  [Not invited]
    後藤勇太朗, 渡邉裕, 佐藤久子
    第67回錯体化学討論会  2017/09
  • キラルイリジウム錯体の合成と性質  [Not invited]
    瀧本和誉, 渡邉裕, 森重樹, 佐藤久子
    第67回錯体化学討論会  2017/09
  • Application of Vibrational Circular Dichroism to Chiral Iridium and Ruthenium Complexes  [Not invited]
    Hisako Sato, Kazuyoshi Takimoto, Jun Yoshida, Akihiko Yamagishi
    第67回錯体化学討論会  2017/09
  • セシウムイオンの土壌中での動態および、汚染土壌の減容化に向けた粘土カラム方式ミニフィールド装置を用いたセシウム除去方法  [Invited]
    佐藤久子
    日本分析化学会中国四国支部主催の第54回日本分析化学会中国四国支部分析化学講習会  2017/08
  • 干渉作用による発光性イリジウム錯体LB膜の発光変化  [Not invited]
    山田 達也, 尾崎 良太郎, 弓達 新治, 門脇 一則, 佐藤 久子
    2017年度 応用物理・物理系学会 中国四国支部 合同学術講演会  2017/07
  • 土壌中の放射性セシウムの特性と酸抽出効果  [Not invited]
    森田昌敏, 山岸皓彦, 法人環境測定品質管理センター, 田村堅志, 物, 材料研究機構, 山下浩, 佐藤久子
    第6回環境放射能除染研究発表会  2017/07
  • 遊星ボールミル粉砕法を併用した汚染土壌の脱セシウム化  [Not invited]
    山下浩, 愛媛大院理工, 田村堅志, 物質, 材料研究機構, 佐藤久子, 媛大院理工, 森田昌敏, 環境測定品質管理センター
    第6回環境放射能除染研究発表会  2017/07
  • マイクロ波処理による汚染土壌の脱セシウム化  [Not invited]
    山岸晧彦, 環境測定品質管理センター, 田村堅志, 物, 材料研究機構, 山下浩, 愛媛, 佐藤久子
    第6回環境放射能除染研究発表会  2017/07
  • 汚染土壌の減容化に向けた粘土化学的手法の開発  [Not invited]
    佐藤久子, 田村堅志, 山下浩, 愛, 大森大輔, ダイキアクシス, 金子芳郎, 山岸晧彦, 森田昌敏, 定品質管理センター
    第6回環境放射能除染研究発表会  2017/07
  • Structure of bombinin H4 containing a D-allo-isoleucine by solid-state VCD and solid-state NMR  [Not invited]
    Yumi Ozawa, Batsaikhan Mijiddorj, Hisako Sato, Namsrai Javkhlantugs, Akira Naito, Kazuyoshi Ueda, Izuru Kawamura
    IDAR2017  2017/07
  • Structural difference of functional peptide fibers between L-Phe-L-Phe-OH, L-Phe-D-Phe-OH and D-Phe-D-Phe-OH  [Not invited]
    Yumi Ozawa, Batsaikhan Mijiddorj, Hisako Sato, Namsrai Javkhlantugs, Akira Naito, Kazuyoshi Ueda, Izuru Kawamura
    IDAR2017  2017/07
  • Enhanced emission from hybrid Langmuir-Blodgett films of amphiphilic iridium complexes with the exfoliated nanosheets on a metal layer  [Not invited]
    Ryotaro Ozaki, Tatsuya Yamada, Kazunori Kadowaki, Hisako Sato
    9th International conference on Molecular Electronics and Bioelectronics  2017/06
  • Solid State VCD Spectra of Amino Acids: Effects of Interplay between Two Chiral Centers in Isoleucine  [Not invited]
    Hisako Sato, Izuru Kawamura, Fumi Sato, Akihiko Yamagishi
    Chirality2017  2017/06
  • 立体反転によって誘起されるペプチドファイバーの形態変化と固体NMRによる構造解析  [Not invited]
    尾澤夢実, 佐藤久子, 内藤晶, 川村出
    高分子学会17-1NMR研究会  2017/05
  • 繊維状粘土に取り込まれた希土類錯体からなる多機能性無機有機複合発光体の光安定性  [Not invited]
    海崎純男, 城谷 大, 岩松雅子, 加藤由美子, 佐藤久子, 山崎鈴子, 梶原 篤
    第33回希土類討論会  2017/05

MISC

Industrial Property Rights

Awards & Honors

  • 2017/09 日本粘土学会 論文賞
     
    受賞者: 佐藤久子
  • 2008/06 日本女性科学者の会 第13回奨励賞
     無機ナノシートの電子デバイスの研究 
    受賞者: 佐藤久子
  • 2003/09 日本粘土学会 平成15年度日本粘土学会論文賞
     
    受賞者: 佐藤久子;土屋卓久;河村雄行

Research Grants & Projects

  • 不均一系触媒作用を目指した無機キラルナノスクロール創製への挑戦
    日本学術振興会:科学研究費助成事業 挑戦的研究(萌芽)
    Date (from‐to) : 2020/07 -2023/03 
    Author : 佐藤 久子
  • The development of liquid crystalline metal complex host for labile and chiral metal complexes
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2019/04 -2022/03 
    Author : 吉田 純, 佐藤 久子, 渡辺 豪
  • 汚染土壌中のセシウム固定化機構の解明と実用減容化技術の開発
    環境省:環境研究総合推進費
    Date (from‐to) : 2019/04 -2022/03 
    Author : 田村堅志, サブテーマ, リーダー佐藤久子
  • 汚染土壌中の吸着セシウムイオンのミクロ構造の解明
    日本学術振興会:科学研究費助成事業 基盤研究(B)
    Date (from‐to) : 2017/04 -2021/03 
    Author : 田村 堅志, 佐久間 博, 佐藤 久子, 小暮 敏博, 森本 和也
     
    福島第一原子力発電所の事故によって放出された放射性セシウムによる汚染土壌では、風化黒雲母が他の粘土鉱物よりも放射性セシウムを強く吸着し、脱離を困難にしているといわれている。この問題に対して粘土化学的な立場から吸着セシウムイオンの吸着ミクロ構造を調べ、吸着したセシウムイオンが安定化に至る機構解明を進めている。 我々は風化黒雲母のセシウム吸着サイトとして、ヒドロキシアルミニウムが層間に入って形成されたHydroxy-interlayered vermiculite(HIV)中の“くさび型空間”が有力であると考えている。福島地域の酸性土壌環境では、雲母質鉱物の部分的溶解によってアルミニウムが一旦放出され、その後再吸着して層間でくさび構造(一部ヒドロキシル化)が形成される。このヒドロキシアルミニウム化過程は、イオン交換容量の減少をもたらすが、セシウムの移動性に少なからず影響していていると考えられる。今回、HIV様層間構造をもつヒドロキシアルミニウム変質黒雲母を調製し、マグネシウムイオンによる脱離実験を実施した。並行して133Cs-NMR, 27Al-NMR測定によりその吸着状態の詳細を調べた。アルミニウムヒドロキシル化による構造変化が、セシウムイオンの移動性に大きく影響を及ぼしていることが確認できた。本研究では完全にヒドロキシルアルミニウムイオンで置換されたと風化黒雲母よりも、一部カリウムイオンが残存する不規則混合層(くさび空間)をもつ風化黒雲母の方がセシウムの安定性が高いことが明らかになった。 また、福島産天然風化黒雲母にセシウムを吸着させた試料を調製し、種々の溶液でセシウム溶出実験を実施した結果からは、セシウムは風化黒雲母の表層部くさび空間に選択的に吸着していると推定された。
  • 発光性キラルイリジウム錯体膜を用いたアップコンバージョンシステムの構築
    日本学術振興会:科学研究費助成事業 基盤研究(B)
    Date (from‐to) : 2017/04 -2021/03 
    Author : 佐藤 久子, 吉田 純, 梅村 泰史
     
    本研究の目的は、粘土面の2次元規則性に整合したキラル錯体間相互作用に着目し、高密度に規則配列した分子間でのエネルギー移動と3重項消滅反応によって光エネルギーアップコンバージョン系を実現することである。今までに本申請者らは、ラングミュア・ブロジェット法(粘土LB法)により両親媒性イリジウム(III)錯体と粘土鉱物ナノシートとの複合膜(厚さ数ナノメーター)を製造し、光エネルギー集約系や多色発光酸素センサーデバイスを実現してきた。2017年度は、長鎖アルキル基を有するイリジウム錯体を用いて、粘土LB法によりドナーとアクセプターとして働く2種の錯体を、混合割合を変えて合成サポナイトとの複合LB膜を製造した。得られた膜において、効率的なドナーからアクセプターへのエネルギー移動を利用した酸素センシングを実現し、オープンアアクセス論文として報告した。さらに、粘土ナノシートとの整合性の良いかさ高い配位子をもつキラルイリジウム(III)錯体を合成し、コロイド状合成サポナイトとの複合化を行った。低い吸着率においても、キラル体のほうがラセミ体よりも発光強度や発光寿命が長くなることがわかった。次に、キラルイリジウム錯体を吸着した合成サポナイト面を用いて、消光剤であるキラルルテニウム錯体を用いて挙動を調べた。その結果、高い選択率でエナンチオ選択性が見られた。同じ系のメタノール溶液中では、このようなキラル識別効果は見られず、粘土面上に均一に配向したイリジウム錯体が、その配位子のつくるミクロなキラルポケットを用いてキラル識別しているものと考察した。この結果は王立化学会のNew J. Chemの2018年4月号の裏表紙に採用された。さらにこのような粘土面での分子認識機構の解明に振動円二色性分光法の適用を検討した。また、分担者と共同の論文は日本液晶学会の表紙に採用された。
  • 多次元赤外円二色性分光法の開発
    国立研究開発法人科学技術振興機構:未来社会創造事業
    Date (from‐to) : 2018/11 -2021/03 
    Author : 佐藤久子
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    Date (from‐to) : 2017/04 -2019/03 
    Author : YOSHIDA Jun, SATO Hisako
     
    The ruthenium complexes showing NIR absorption in response to redox have been developed in order to utilize NIR in the sun light efficiently. We found that ruthenium (III) tropolonato complexes show NIR absorption after mono-electron oxidation. We concluded that tropolone derivatives work as non-innocent ligands in the oxidized complexes in comparison with ruthenium acetylacetonato derivatives. The oxidized species of the ruthenium complexes were unstable in solution, whereas they were stabilized in hybridization with clay minerals. We further introduced long alkyl chains into the ruthenium complexes in expecting to improve the molecular arrangement. Although we have not yet clarified the effect of the alkyl chains on the molecular arrangement on the clay surface, we found that the complexes effectively work as chiral dopants for liquid crystals.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    Date (from‐to) : 2016/04 -2019/03 
    Author : SATO Fumi
     
    The present work was motivated by the recent attention to the presence of D-amino acids in animals and also to their biological activities. It was attempted to determine the DL ratios of amino acids in the rat brain. Firstly a new type of a probe for detecting amino acids was developed on the basis of an emitting iridium(III) complex. The results may promise a possibility of developing an in situ photo-sensor of amino acids in biological systems. Secondly, for the purpose of in vivo analyses of a D-amino acid in proteins, vibrational circular dichroism (VCD) was applied for isoleucine with two chiral centers. The work provides the first experimental VCD report of isoleucine in a solid state. Thirdly the free amino acids in the cerebellum and cerebrum of rats were extracted and their DL analyses were attempted. The extracted amino acids were labelled for spectroscopic detection. The method of determining the DL ratio of a labelled amino acid chromatographically has been established.
  • D-アミノ酸への転換反応追跡用次元拡張型振動円二色性分光法の開発
    日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    Date (from‐to) : 2016/04 -2018/03 
    Author : 佐藤 久子
     
    本プロジェクトでは、(1)次元拡張型VCD装置の開発を行い、(2)ペプチドオリゴマー中のD-アミノ酸の検出を目指した研究を行った。(1)に関しては、VCD装置のバージョンアップを行い、ベースラインの長期間安定性を実現し、信号/雑音比をあげて微弱シグナルの測定を可能とした。それと同時に直線偏光の測定も可能とし、固体VCD法の開発をおこなった。(2)(2A)粘土鉱物(モンモリロナイト)表面にキラルな金属錯体Δ-あるいはΛ-[Ru(phen)3]2+(phen=1,1-phenanthroline)を吸着させて、モンモリロナイト表面にキラル認識場を作製した。インターカレートした錯体のΔ、Λ体に対応して反転したシグナルを得ることができた。さらに、この試料中にキラル物質として有機分子であるR,-あるいはS-BINOL(1,1’-bi-2-naphthol)を吸着させ、モンモリロナイト面上におけるキラル分子間の相互作用を検討した。モンモリロナイトを含めた3成分系にVCD法を適用した結果、金属錯体との相互作用により柔らか分子の有機分子BINOLがコンフォーメーションを変える証拠を得ることができた。VCD法を層状化合物に初めて適用した例である。(2B)パーフルオロ基をもつ低分子量ゲル化剤とアルキル基をもつ2成分系のキラルゲルに対してVCD法を適用した。ゲル化速度と熱力学的安定性への影響を検討した。特に、ゲル化剤のキラリティの影響(立体化学的効果)の検討をおこなった。VCD吸収がゲル化に伴い増大してく現象を観察した。(2C)ペプチドオリゴマー関連のテーマとしては、抗菌ペプチド ボンビニンH2,H4のD体アロイソロイシン残基の役割に関して領域内で共同研究をおこなった。VCDの結果から1残基目の側鎖と2残基目の側鎖の関係がH2ではトランス型、H4ではシス型であることがわかった。
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    Date (from‐to) : 2014/04 -2018/03 
    Author : Sato Hisako
     
    The VCD spectroscopy was applied to reveal the kinetic and thermodynamic aspects of gelation by a chiral low molecular gelator with perfluoroalkyl groups. An attention was paid to the helical nature of a perfluoroalkyl chain on the formation of gel fibrils. It was noted that VCD signals were remarkably enhanced during the gelation process. The three-dimensional gelation was compared with the formation of a two-dimensional Langmuir-Blodgett (LB) film. Some thicker rods with helical grooves were observed in the LB films, which were regarded as a precursor of gel fibrils.
  • D-アミノ酸への転換反応追跡用次元拡張型振動円二色性分光法の開発
    文部科学省 科学研究費補助金(新学術領域(研究提案型)):
    Date (from‐to) : 2016/04 -2018/03 
    Author : 佐藤久子
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    Date (from‐to) : 2014/04 -2017/03 
    Author : Kaizaki Sumio, YMAZAKI Suzuko, NAKATA Hiroyasu, MATSUMURA Takeko, KAJIWARA Atsushi, SHIROTANI Dai, IWAMATSU Masako, KATO Yumiko, TOYA Keiko
     
    Multifunctional luminescence such as temperature dependent luminescence for the phosphors, Ligand@SEP:Ln, are exhibited where light harvesting ligands such as 1,10-phenanthroline (phen) and/or 1,4-dibenzoylbenzene(dbb) coordinate with Eu(III) and Tb(III) complexes embedded into fibrous magnesium silicate clay sepiolite(SEP) in which the magnesium ion are ion exchanged. For these phosphors, a variety of the photostability are observed under UV (300 nm) irradiation; decreasing 50 % of the 4f-4f luminescence intensity after 10 min for phen@SEP:Eu3+, probably due to the decomposition of phen, whereas increasing 20 % of the intensity for dbb@SEP:Eu3+ and dbb@SEP:Tb3+ after 20 min. This may be elucidated by the thermoluminescence in connection with the trapped electrons in the SEP clay. The photostable practically usable naked eye visible phosphor is prepared by considering the difference of ligands in photostability.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2014/04 -2017/03 
    Author : Sato Hisako, TAMURA Kenji
     
    The molecular devices for photo-sensing oxygen gas are manipulated by using cyclometalated iridium(III) complexes as an emitting element. In the attempts, an ultra-thin film hybridizing a luminescent Ir(III) complex with a clay mineral (synthetic saponite) was prepared by applying the modified Langmuir-Blodgett method. Such hybridization resulted in the enhancement of robustness of films and the reliability of sensing. By use of artificially controlled layering, the interlayer distance between the donor and the acceptor was changed to tune energy transfer efficiency. The results indicate the possibility of developing of multi-emitting device, efficient energy harvesting or chiral sensing on clay surface.
  • 汚染土壌の減容化実現に向けた粘土化学的手法の開発
    環境省:環境研究総合推進費補助金
    Date (from‐to) : 2014/04 -2017/03 
    Author : 佐藤久子
  • 球状ラポナイトを利用したキラル香料成分のための分取カラムの開発
    JST:マッチング探索
    Date (from‐to) : 2015 -2016 
    Author : 佐藤久子
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    Date (from‐to) : 2012/04 -2015/03 
    Author : MORIMOTO KAZUYA, KOGURE Toshihiro, TAMURA Kenji, SATO Hisako, YAMAGISHI Akihiko
     
    Since the explosion accident at the Fukushima nuclear power plant, decontamination of a huge amount of soil polluted with radioactive cesium became the urgent issue. These Cs isotopes stay as ions in the soils near the ground surface for a long period, since they are strongly fixed in the interlayer spaces of clay minerals. Because vermiculite clay has an extremely high adsorption capacity for Cs ions compared to other minerals, it can play an important role in the environmental fate of radioactive cesium in the polluted area. In the present work, we have elucidated the state of Cs ions fixed in a vermiculite clay, and examined the possibility of desorption of Cs ions.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2011/04 -2015/03 
    Author : SATO Hisako, NAGAOKA Shinichi, TAMURA Kenji
     
    By using cyclometalated iridium(III) complexes as an emitting element, photo-responsive molecular devices for sensing oxygen gas was manipulated. A thin film was prepared by hybridization with clay minerals. In such a film, luminescent Ir(III) complexes were hybridized with clay minerals in order to enhance robustness and reliability. As a result, nanometer-thick hybrid films were constructed by applying the modified Langmuir-Blodgett method. The achievement of multi-emitting properties in response to oxygen pressure has been demonstrated.
  • 2次元に制限された粘土鉱物表面を用いた迅速光学分割カラムの開発
    JST:研究成果展開事業 研究成果最適展開支援プログラム A-STEP探索タイプ
    Date (from‐to) : 2014 -2015 
    Author : 佐藤久子
  • 積層ナノ薄膜を用いたリアルタイム多重発光性極微量酸素センサの開発
    JST:研究成果展開事業 研究成果最適展開支援プログラム A-STEP 顕在化タイプ
    Date (from‐to) : 2012 -2013 
    Author : 中野 信夫
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    Date (from‐to) : 2011 -2013 
    Author : SATO Hisako, SUEMATSU Takashi
     
    Recently the transparent flexible semiconductors that can be fabricated into a form of ultra-thin films are a target material for the development of low energy-consuming devices. Although little attention has been paid to a class of inorganic layered compounds, they are a promising candidate particularly when they are exfoliated to individual nanosheets. In the present work, a normally-on FET was fabricated by contacting two regions on a glass substrate: the one side was a cast film of perovskite-type niobate as n-type photosemiconductor and the other a cast film of synthetic saponite as an insulator. The current-voltage (I-V) characteristics were obtained under the illumination of light (340 nm). This is the first FET device based on clay minerals.
  • 単一膜で多機能性を有する有機・無機ハイブリッド発光デバイスの開発
    日本板硝子材料工学助成会:
    Date (from‐to) : 2011 
    Author : 佐藤久子
  • キラル金属錯体ネットワーク膜の製造とVCD/RASコンカレント測定法の開発
    JST:戦略的創造研究推進事業(さきがけ)
    Date (from‐to) : 2006/10 -2010/03 
    Author : 佐藤久子
  • 発光性イリジウム錯体LB膜を用いたセンシングデバイス
    JST:研究成果展開事業 研究成果最適展開支援プログラム A-STEP探索タイプ
    Date (from‐to) : 2010 
    Author : 佐藤久子

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    Date (from-to) : 2020
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愛媛大学教員活動実績

教育活動(B)

担当授業科目(B01)

  • 2019, the first semester, under graduate, 卒業研究Ⅰ
  • 2019, the first semester, master course, 物質物性化学特論
  • 2019, the first semester, master course, 化学ゼミナールⅠ
  • 2019, the first semester, master course, 分子科学課題演習I
  • 2019, the first semester, doctor course, 物質機能科学特論Ⅳ


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